Ausgabe / Edition 09.94 Bestell-Nr. / Order-No. E20125-D0001-S302-A1-7600
Specification
Universal Serial
Interface Protocol
USS Protocol
Siemens AG 1994 All Rights Reserved
Authors:
Walter Möller - Nehr ing, Siemens A G, ASI 1 D S P , Er langen
Wolfgang Bohrer , Siemens A G, ASI 1 D S P , Er langen
Copying of this document, and giving it to others and the use or
communication of the contents thereof are forbidden without
express authority. Offenders are liable to payment or damages.
All rights reserved, in particular with regard to the granting of a
patent or the registration of a utility model or design.
We have checked the contents of this document to ensure that
they coincide with the described hardware and software.
However, differences cannot be completely excluded, so that we
do not accept and guarantee for complete conformance.
However, the information in this document is regularly checked
and necessary corrections will be included in subsequent
editions. We are grateful for any recommendations for
improvement.
USS is a r egis tered tradem ar k of Siem ens .
SIMOREG is a r egis tered tradem ar k of Siem ens .
SIMOVERT is a r egis tered tradem ar k of
Siemens.
Contents, release, literature
Specifications, USS protocol I
E20125-D0001-S302-A1-7600
Contents
Section A: Protocol specification
1. Introduction...........................................................................................................................................1
2. Telegram trans fer .................................................................................................................................2
2.1. Cyclic telegram trans fer ........................................................................................................................2
2.2. Acyclic telegram tr ansf er.......................................................................................................................2
3. Broadcast.............................................................................................................................................2
4. Telegram s truc ture................................................................................................................................3
4.1. Data coding .......................................................................................................................................... 3
4.2. Telegram length (LGE) .........................................................................................................................3
4.2. 1. Variable t elegr am length .......................................................................................................................3
4.2. 2. Fixed telegram length ...........................................................................................................................3
4.3. Assigning the addres s by te (A DR) ........................................................................................................4
4.4. BCC generat ion....................................................................................................................................5
5. Data t r ans fer pr oc edur e........................................................................................................................6
5.1. Data t r ans fer handling...........................................................................................................................6
5.1.1. Cycle time .............................................................................................................................................7
5.1.2. Start interval.........................................................................................................................................8
5.2. Monitoring mechanisms and error responses........................................................................................8
5.2. 1. Time m onitoring....................................................................................................................................9
5.2. 1.1. Response delay t im e ............................................................................................................................9
5.2. 1.2. Telegram r es idual r un time....................................................................................................................9
5.2. 2. Proces s ing r ec eiv ed telegram s .............................................................................................................9
5.2. 3. Diagnostic r es our c es for c hec k ing the rec eiv e function........................................................................ 10
5.3. Mirror telegram ................................................................................................................................... 11
6. Definitions........................................................................................................................................... 12
6.1. Charact er r un time.............................................................................................................................. 12
6.2. Compress ed telegram r es idual r un time.............................................................................................. 12
6.3. Maximum telegram r es idual r un time................................................................................................... 12
Section B: Physical interface and bus structure
1. Topology...............................................................................................................................................1
2. Data t r ans fer technology.......................................................................................................................2
2.1. Cable characteristics.............................................................................................................................2
2.2. Cable length .........................................................................................................................................4
2.3. Interface characteristics........................................................................................................................4
2.4. Data transfer rate..................................................................................................................................5
3. Data t r ans fer techniques.......................................................................................................................6
3.1. Bit coding.............................................................................................................................................. 6
3.2. Character frames..................................................................................................................................6
4. Configuration guidelines........................................................................................................................7
4.1. Cable routing ........................................................................................................................................ 7
4.2. Potential bonding..................................................................................................................................7
4.3. Screening .............................................................................................................................................7
4.4. Term ination t ec hnology , connec tor as s ignm ents...................................................................................8
4.5. Bus t er m ination.....................................................................................................................................9
4.6. Recommended c ir c uit ......................................................................................................................... 11
Contents, release, literature
II Specifications, USS protocol
E20125-D0001-S302-A1-7600
Section C: Defining the net data for drive applications
1. Introduction........................................................................................................................................... 1
2. General str uctur e of t he net dat a bloc k ................................................................................................. 2
3. Parameteriz ation of the USS prot oc ol at a ser ial interf ac e.................................................................. 4
3.1. Parameter s ett ing for 6S E 21, 6SE 30 ( M ic r o M as ter) S IMOVERT conv er ters and S IMOREG K 6RA 24. 4
3.2. Parameter s ett ing for S IMOVE RT Mas ter Driv es .................................................................................. 7
4. PKW area........................................................................................................................................... 10
4.1. Str uc ture of t he P K W area ( par am eter ID value)................................................................................. 10
4.1. 1. PKW area f or a fixed telegram length .................................................................................................. 10
4.1. 2. PKW area wit h v ar iable telegram length.............................................................................................. 11
4.2. Description of the individual P K W elements ........................................................................................ 11
4.2.1. Parameter ID (PKE) ............................................................................................................................ 11
4.2. 1.1. Task- and response ID........................................................................................................................ 11
4.2. 1.2. Paramet er c hange r epor t.................................................................................................................... 16
4.2.1.3 Parameter number (PNU)................................................................................................................... 18
4.2. 2. Index ( IND)......................................................................................................................................... 18
4.2. 3. Parameter v alue ( P WE)...................................................................................................................... 23
5. PZD area............................................................................................................................................ 25
5.1. Structure of the PZD area................................................................................................................... 25
5.2. Description of the individual P ZD elements ......................................................................................... 26
5.2. 1. The control wor d and s tat us wor d ....................................................................................................... 26
5.2. 2. Setpoints / actual values..................................................................................................................... 32
5.2. 3. Broadcas t mec hanis m ........................................................................................................................ 32
6. Data transfer format for the net data................................................................................................... 33
7. Configuring t he prot ocol on the bus syst em......................................................................................... 36
8. Examples............................................................................................................................................ 38
8.1. Fixed telegram length ......................................................................................................................... 38
8.2. Variable t elegr am length..................................................................................................................... 41
Appendix
Over v iew: T elegr am s truc ture for the USS-protokoll ....................................................................................... 1
The O pt ional Broadcast Mechanism of the USS-Protocol.................................................................................. 2
Contents, release, literature
Specifications, USS protocol III
E20125-D0001-S302-A1-7600
Editions
Edition Order No. Date Status
1st E dition, S ec tion A E31930 - T 9011 - X - A 1 January ' 92 Published
1st E dition, E nglis h
Sect ion A E31930 - T 9011 - X - A 1- 7600 January ' 92 Published
1st E dition
Applications
E31930-T9012-X-A1 April '92 Published
Errors, to the 1st Edition
Applications E31930-T9012-X-A2 Oc t ober '92 Published
Function expans ion for
SIMOVERT Master
Drive and general
update.
Not published as
application
E31930-T9012-X-AXX August '93 Preliminary
Summary of the
documents
E31930-T 9011 and
E31930-T9012
(d) E20125- D001- S 302- A 1
(e) E20125- D001- S 302- A 1- 7600 September ' 94 New Edition
Brief des c r iption of the changes :
August 1993:
• Specif ic ation f or S IMOVE RT Mas ter Dr iv es .
• The r es tric tion regar ding a fixed telegram length f or tas k telegr ams f rom t he m aster to t he slave has been
withdrawn. W hen a v ar iable telegram length has been par am eteriz ed, t his is pos s ible in both dat a trans fer
direct ions (Master → S lav e → Master).
• Expansion in t he index wor d ( IND) in the high byte f or text t r ans fer for SIMOVE RT FC/ V C/SC
• The t ex t char ac ter s equenc e has been c hanged for data t r ans fer v ia the bus.
Septem ber 1994:
• Sect ion C has been updated: P oint 3: P ar am eteriz ation
• New in Sect ion C: Point 6: Us eful dat a trans fer form at
• Supplement , Sec tion B: Phy s ic al interface and bus s truc ture
• The mas ter c an now be loc ated at any pos ition on t he bus .
• Recommendation f or dis play par am eters for B US - and interface diagnos tics .
• Assignm ent of the mos t significant bit in the addres s by te for s pec ial telegram s
• Broadcas t def inition, S ec tion C
• Bits 11-15 in the index have been defined, convert er-specif ic
• Section B: Designat ions (A) and (B) have been replaced by RS485P and RS485N
Contents, release, literature
IV Specifications, USS protocol
E20125-D0001-S302-A1-7600
Note
These ins truc tions do not purpor t t o c ov er all details or v ar iations in equipm ent, nor to prov ide for ev er y
possible contingency to be met in connec tion wit h ins tallat ion, operation or maintenance.
Should fur ther inform ation be desir ed or s hould par ticular pr oblem s ar is e whic h ar e not cov er ed
sufficiently for the purc has er ’s pur pos es , t he m att er s hould be r eferred to t he loc al S iem ens s ales off ic e.
The content s of t his Instruc tion Manual s hall not becom e par t of or m odify any pr ior or ex is ting
agreement , com m itt m ent or r elationship. T he s ales c ontrac t cont ains the ent ir e obligation of S iem ens .
The warr anty c ontained in t he c ontrac t bet ween the parties is the sole warr anty of Siem ens . Any
statements c ontained herein do not cr eate new warr anties or m odify t he ex is ting warr anty.
Literature
/1/: PROFIBUS profile: V ar iable- s peed dr iv es
VDI / VDE Guideline 3689
Draft, January 1993
/2/ : RS485 Recommended Standard
EIA 485: STANDA RD FO R E LE CTRI CA L CHA RA CTERISTICS
OF GENERATOR AND RECEIVER FOR USE IN
BALANCED DIGITAL MULTIPOINT SYSTEMS
EIA S tandard A pr il 1983
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A: Protocol specification
Specification, USS protocol A - 1
E20125-D0001-S302-A1-7600
A: Protocol specification
1. Introduction
The USS prot oc ol ( Univ er s al S er ial Inter face P r otocol) defines an ac c es s technique ac c or ding to t he m as ter-
slave princ iple for c om m unic ations v ia a s er ial bus . T his als o inc ludes , as s ub- quantit y , t he point-t o- point
connection.
Essential f eatures of t he US S prot oc ol ar e:
•It s uppor ts a m ulti-point-c apable c oupling, e. g. EIA RS 485 har dwar e
•Mast er - s lav e ac c es s technique
•Single master system
•Max. 32 nodes ( m ax . 31 slav es )
•Simple, r eliable telegram fram es
•Easy to implem ent
•Operation wit h either v ar iable or fixed telegram lengths.
One mas ter and a m ax im um of 31 slav es c an be c onnec ted t o the bus. T he indiv idual s lav es ar e s elec ted by
the mas ter v ia an addr es s c har ac ter in the t elegr am . A s lav e itself can nev er transm it wit hout f ir s t being
request ed to do so, and direc t mes s age trans fer between t he indiv idual s lav es is not possible. Comm unic ations
is realized in the half - duplex m ode.
The mast er f unction cannot be transf erred t o another node (single-master system).
A bus configuration f or a dr iv e applic ation is illus trated in t he following diagram .
SIMOVERT/
SIMOREG
"Slave"
Hi
g
her-level
computer
"Master"
SIMOVERT/
SIMOREG
"Slave"
SIMOVERT/
SIMOREG
"Slave"
SIMOVERT/
SIMOREG
"Slave"
Fig. 1.1: Serial coupling between SIMOREG- / SIMOVERT drive converters (slaves) with a higher-level computer as master.
The electric al and m ec hanic al interface c har ac teris tics ( har dwar e) ar e not part of the protocol s pec ification. The
definit ions and r ec om m endations r egar ding the dat a trans fer technology , t he data tr ans fer technique and bus
configurat ion are described in Section B: ”Physical interf ace and bus conf iguration” of this specif ication.
A: Protocol specification
A - 2 Specification, USS protocol
E20125-D0001-S302-A1-7600
2. Telegram transfer
Generally, a differentiation can be made between cyclic and acyclic t elegram t r ansfer. In drive technology, only
cyclic telegram t ransfer is used. The master station is responsible for cyclic telegram transf er, whereby all slave
nodes are addres s ed, one af ter the ot her , in ident ic al time interv als .
2.1. Cycli c t eleg ram t ransfer
Drive technology requires def ined response t imes for the open-loop and closed-loop control t asks, and thus a
rigidly cyclic telegram tr ansf er:
The mast er cont inually transmit s t elegrams (task telegrams) to the slaves and waits for a response t elegram
from the addres s ed s lav e.
A slave m us t send a r es pons e telegram , if
•it rec eiv ed a telegram , err or - free and
•it was addr es s ed in this telegram .
A slave c annot send, if these c onditions ar e not f ulfilled or the slave was addr es s ed in the broadc as t mode.
For the mas ter, a connec tion is es tablished to t he appr opr iate slave if it r ec eiv es a r es pons e telegram from the
slave af ter a defined proc es s ing time ( r es pons e delay time) .
In cy c lic telegram trans fer, t he s lav e nodes m us t monitor telegram trans fer for failure.
Some of t he net data, which are included in t he cyclic t elegram, are provided f or service and diagnost ics. The
net dat a transf er for data technology is described in Section C: ”Defining the net dat a for drive applicat ions”.
2.2. Acycli c t eleg ram t ransfer
Generally, t elegram transf er is cyclic.
Cyclic and acyclic telegram t ransfer cannot be used simultaneously.
Service and diagnostic tasks can also be run in acyclic operation.
In acy c lic oper ation, the mas ter s ends telegram s to t he s lav es at irr egular intervals . T he s lav e r es ponds to t he
conditions def ined for cyclic operation.
For ac y c lic telegram trans fer, slav es c annot monitor for t elegr am failure.
3. Broadcast
In t he br oadc as t mode, t he m as ter trans m its a telegram to all slaves on the bus. I n this c as e, t he " B r oadc as t
bit" in the t as k telegram, in t he addr es s by te, is s et t o logic al 1 ( r efer to Sec tion 4. 3, assigning the addres s by te
(ADR)) . T he addr es s bits ar e ineff ec tive. T he indiv idual s lav es m ay not t r ans m it a respons e telegram aft er
receiving a br oadc as t t elegr am .
The use of a broadc as t t elegr am r equir es other definit ions at t he applic ation level ( c om m on telegram length,
assignment of the net data content s to nodes, et c .). For a definit ion of t he net dat a c ontent s for br oadc as t,
refer to Sec tion C, P oint 5: P r oc es s data - B r oadc as t.
A: Protocol specification
Specification, USS protocol A - 3
E20125-D0001-S302-A1-7600
4. Telegram structure
Each t elegr am ( Fig. 4.1) s tarts with t he S TX s tart c har ac ter ( = 02 hex) , f ollowed by the lengt h s pec ification
(LGE ) and the addres s by te (A DR) . T he net char ac ters then f ollow. The telegram is term inated by the BCC
(block check character).
STX LGE ADR 1. 2.
n
BCC
ne t ch ar acte rs
Fig. 4.1: Telegram structure
For wor d inform ation (16 bit) in the net data block , t he first byte is alway s the high byte (firs t char ac ter) and then
the low byte (s ec ond c har ac ter) . T he c or r es ponding is v alid for double wor ds : F ir s t, the high word is s ent,
followed by the low word.
The ident ification of t asks in t he net characters is not part of the prot ocol. The cont ents of the net dat a for drive
converters is handled in S ec tion C.
4.1. Data coding
The inf or m ation is c oded as follows:
•STX (start of t ext): ASCII characters: 02 hex
•LGE ( telegram length): 1 byte, includes the telegram lengt h as bi nar y number,
refer to Secti on 4.2
•ADR (address byte): 1 byte c ontains the slave addr ess and the telegr am type,
binar y c oded; refer t o S ec tion 4. 3
•Net char ac ters: Each one byte, the content s are dependent on the t ask
•BCC: 1 byte bloc k c hec k c har ac ter,
generation, refer t o S ec tion 4.4
4.2. Tel egram l eng t h (LG E )
The t elegr am length is v ar iable.
The t elegr am length is s pec ified in t he 2nd telegram by te.
Depending on the configuration, fixed telegram lengths c an be defined.
For fixed telegram lengths, dif ferent t elegr am lengths can be us ed for eac h s lav e node on the bus.
The max im um tot al length of a telegram is 256 by tes.
The actual lengt h of t he tot al telegram is two char ac ters longer than LGE , as the f ir s t t wo c har ac ters ( S TX and
LGE) ar e not counted.
Only the net c har ac ters ( quantit y n) , addres s by te (A DR) and the block c hec k c har ac ter (B CC) ar e inc luded in
the t elegr am length. Thus, t he telegram length is obtained f r om :
LGE = n + 2. { 1 ≤ LGE ≤ 254 }
A maxim um of n = 252 net c har ac ters ( 252 net dat a by tes) c an be trans ferr ed per telegram .
4.2. 1. Variabl e t eleg ram len gth
For v ar iable length t elegr am s , t he num ber of net c har ac ters is dependent on t he par ticular task ( m as ter →
slave).
4.2. 2. Fi xed teleg ram len gth
For telegram trans fer with a prev ious ly defined f ix ed length, the number net char ac ters within a t elegr am is
fixed, e. g. 6-wor d telegram , i. e. 12 net c har ac ters .
A: Protocol specification
A - 4 Specification, USS protocol
E20125-D0001-S302-A1-7600
The prot ocol must be limited to a fixed length at the user level when conf iguring the bus system. (also ref er t o
Sect ion C)
Diff er ent t elegr am lengths c an be defined f or s lav es c onnec ted t o a bus .
4.3. Assigning the address b yt e ( ADR)
In addit ion to t he node num ber s , addit ional inform ation is c oded in the addres s by te:
The individual bits in the addres s by te are as s igned as illus trated.
= 1: M irro r tele
g
ram, refer to S ection 5.3
= 0: N o mirr or te le
g
ram
= 1: Broadc ast, addre ss bits
(
b it N os. 0 to 4
)
are not ev aluated
= 0: N o broa dcast
S lave nod e No. 0- 31
Bit No.
765
4
3210
= 1: S pe cia l tele
g
ra m , ex planation refer belo w
= 0: S tandard, bits 0 to 6 are v alid, and must be ev aluated
STX LGE ADR 1. 2. n BCC
n net c haracters
Fig. 4.2: Assignment of the address bytes (ADR)
Bit
7Bit
6Bit
5 Significance
0 0 0 Standard data t r ans fer for conv er ters .
Node numbers ( bits 0 to 4 are ev aluated)
010
Mirror telegram : T he node num ber is ev aluated and t he addr es s ed s lav e r eturns the
telegram , unchanged, t o the mas ter ( r efer to 5. 3 M ir r or telegram)
0 0 1 Br oadc as t: The node number is not evaluated. ( r efer under 3. Br oadc as t)
1xx
Special t elegr am : T he telegram is r ejec ted by all s lav es , where no s pec ial telegram is
defined. It is not perm is s ible that the t elegr am is ev aluated (r efer to 5.4 S pec ial
telegram)
Table 4.1: Truth table of the possible combinations of bits 5, 6 and 7 in the address byte (ADR)
It is n ot permi ssible that masters tran smit non-defined combinations and that the slaves respond to
these.
A: Protocol specification
Specification, USS protocol A - 5
E20125-D0001-S302-A1-7600
4.4. BCC gen erat io n
The f ollowing ex am ple s hows how the BCC is gener ated:
BCC = 0, bef or e the fir s t char ac ter of a t elegr am is r ec eiv ed ( S TX)
BCC 0 0 0 0 0 0 0 0
After the f ir s t char ac ter has been r ec eiv ed: BCCnew = BCCold EXOR "first character"
(EXOR = exclusive OR logic operation)
BCCold = 0 0 0 0 0 0 0 0
EXOR
"f ir s t char ac ter" = 0 0 0 0 0 0 1 0 ( ^ STX)
________________________________________________
BCCnew = 0 0 0 0 0 0 1 0
After eac h additional char ac ter has been r ec eiv ed, t his is E X OR’d wit h B CCold EXOR, in or der to regener ate
BCCnew, e. g. :
BCCold = 0 0 0 0 0 0 1 0
EXOR
"sec ond c har ac ter"= 1 1 0 1 0 1 1 0
________________________________________________
BCCnew = 1 1 0 1 0 1 0 0
The res ult is the BCC aft er the last net c har ac ter.
A: Protocol specification
A - 6 Specification, USS protocol
E20125-D0001-S302-A1-7600
5. Data transfer procedure
The mast er implement s cyclic telegram tr ansfer. T he master consecutively addresses all slave nodes using a
task telegram. The addressed nodes return a response telegram. In accordance wit h the mast er-slave
procedure, t he s lav e m us t send the res pons e telegram to t he m as ter after hav ing r ec eiv ed a s pec ific task
telegram , bef or e the mas ter addr es s es the next slav e.
5.1. Data transfer handling
The sequenc e in whic h the addres s ed s lav e nodes c an be s pec ified, for ex am ple, by entering the node
numbers (ADR) in a circulating list . If some slaves must be addressed in a faster cycle than others, then a node
number can oc c ur s ev er al times in the cir c ulating list. A point-to-point connection can be implement ed v ia the
circulating list; in this c as e, only one node is entered in the cir c ulating list .
1357210
Master
0
Exam ple for the circulatin
g
listExample of a confi
g
uration
1
3
5
0
7
21
1
3
5
0
1
01
7
21
N o de s 0 an d 1, are addressed tw ice a s freq u en tl
y
as the other no des .
Fig. 5.1: Circulating list
A: Protocol specification
Specification, USS protocol A - 7
E20125-D0001-S302-A1-7600
5.1. 1. Cycle time
Cycle t im e is defined by the t im e for data t r ans fer with t he indiv idual nodes .
00 1 1
Tele
g
ram run tim e, response node 1
Tele
g
ram run tim e, task node 1
Response dela
y
tim e, node 1
Processin
g
tim e in t he ma ster
Tele
g
ram run tim e, response node 0
Tele
g
ram run tim e, task node 0
Response dela
y
tim e, node 0
00
C
y
cle time
t
Fig. 5.2: Cycle time
The cy c le time c annot be prec is ely defined, due to t he inc ons is tent r es pons e delay - and pr oc es s ing times . A
master can implement a fixed cycle time, by determining a maximum cycle time for one configuration, and t hen
defining t his as absolute cycle time. After data has been transferred with the last node, a mast er must wait, until
the def ined cycle time has expired before he can start to address the nodes again.
A: Protocol specification
A - 8 Specification, USS protocol
E20125-D0001-S302-A1-7600
5.1. 2. Start in t erval
The start char ac ter S TX ( =02 hex) is , by itself, not suf ficient f or the slav es to clear ly identif y the start of a
telegram , as the bit c om bination 02/ hex c an als o oc c ur in the net c har ac ters . T hus , befor e S TX, a char ac ter-
less start delay of at leas t 2 charact er run t imes (r efer to Section 6) is s pec ified f or the mas ter. T he s tart
interv al or delay is par t of the t as k telegram .
Only an STX with preceding start interval id entifies a valid telegram st art .
Baud rat e
in bit/s Start in t erval
in ms
9600 2.30 ms
19200 1.15 ms
38400 0.58 ms
187500 0.12 ms
Table 5.1: Minimum start interval for various baud rates
Data t r ans fer is alway s r ealiz ed in the sc hem atic illus trated in F ig. 5. 3 ( half-duplex oper ation).
STX LGE ADR 1. n BCC
Start
interval
Response
delay time
STX LGE ADR 1. BCCBCC
Start
interval
Master se nd s Slave sends
STX
Fig. 5.3: Send sequence
5.2. Monitoring mech ani sms and error responses
When a telegram is r ec eiv ed, t he c or r ec t t elegr am s tart mus t f ir s t be ident ified (start int er v al + STX) , and t hen
the lengt h is ev aluated (LGE) . T he telegram is r ejec ted, if t he length infor m ation does not cor r es pond to t he
select ed v alue for a fixed telegram length or if it is inv alid for a v ar iable telegram length.
Times hav e to be monitored before and dur ing telegram r ec eption (r efer below) .
The
block chec k c har ac ter
(BCC) is gener ated during r ec eption, and aft er the com plete t elegr am has been
read-in, c om par ed with t he r ec eiv ed B CC. T he telegram is not evaluated if these do not coincide.
If a c har ac ter fram e er r or or a par ity er r or has not occ ur r ed in any of t he r ec eiv ed c har ac ters , the node num ber
(ADR) of t he r ec eiv ed telegram c an be ev aluated.
If the addres s by te (A DR) does not coinc ide with t he node num ber ( for the slav e) , or t he ex pec ted slav e node
number (for the mas ter) , t hen the t elegr am is r ejec ted. ( r efer t o 4.3 f or the evaluation of A DR)
A: Protocol specification
Specification, USS protocol A - 9
E20125-D0001-S302-A1-7600
5.2.1. Time monitoring
The master mus t monitor the f ollowing times:
–Response delay time ( s lav e pr oc es s ing time)
–Residual run t im e of t he r es pons e telegram ( r efer to Sec tion 6)
The slave monit or s the f ollowing times :
–Star t delay
–Residual run t im e of t he task telegram ( r efer to Sec tion 6)
5.2. 1.1. Respo nse d elay time
The t im e interv al between t he las t char ac ter of t he task telegram ( B CC) and the start of the res pons e telegram
(ST X ) is k nown as the resp on se del ay t ime (F ig. 5. 3) . T he m ax im um per m is s ible r es pons e delay time is 20
ms; how ever it may no t be l ess t han t he start int erval . I f node x does not res pond within t he m ax im um
possible res pons e delay time, t he " node x does not t r ans m it" er r or m es s age is s tored in the mas ter. T he m as ter
then t r ans m its the t elegr am for the next slav e node.
The " node x does not t r ans m it" er r or m es s age is only deleted after an er r or - free telegram from node x . Node x
is not deleted f r om the cir c ulating list.
5.2. 1.2. Tel egram residual run time
The monitoring of t he telegram r es idual r un time is dependent on t he negotiat ed telegram length.
•Variable t elegr am length
The monitoring of t he m ax . t elegr am r es idual r un time is firs t loaded af ter STX has been r ec eiv ed, wit h the
value, whic h is obtained f or a telegram with 252 pieces of net data. A ft er LGE has been r ec eiv ed ( S ec tion
4.2), i. e. t he nex t char ac ter, t his m onitoring time is loaded with t he c or r ec t value.
•Fixed telegram length
The monitoring of t he m ax im um telegram r es idual r un time c an be dir ec tly s tarted with the cor r ec t value
(it is not neces s ar y to evaluate LG E ) .
5.2.2. Processing received t eleg rams
Only telegram s whic h hav e been r ec eiv ed er r or - free, are pr oc es s ed. T he following rec eiv e er r or s ar e identif ied
(this is true for both t he m as ter and s lav e) :
•Parity errors
•Charact er fram e er r or s
•Incor r ec t t elegr am length (LGE)
•Incorrect BCC
•Telegram r es idual r un time ex c eeded
•Connection interr upted:
- Slav e: T he m as ter ac tivities ar e not monitored at the pr otocol lev el, t he us er lev el c an pr ov ide a
monitor ing function which c an be par am eteriz ed ( bus m onitoring time) .
- Mas ter: T he s lav e does not res pond within t he m ax im um per m is s ible r es pons e delay time.
Slaves do no t send a response teleg ram wh en ad dressed wi t h an in correctly recei ved teleg ram.
A: Protocol specification
A - 10 Specification, USS protocol
E20125-D0001-S302-A1-7600
5.2.3. Diagnostic resources for ch ecking the receive fu nctio n
The int er face s oft war e c an pr ov ide inform ation regar ding c om m unic ations s tat us for com m unic ation int er face
diagnostics.
The diagnostic inform ation should be able to be display ed for s lav es , on t he c onv er ter operator c ontrol panel
(diagnost ic par am eters US S interface) .
The f ollowing diagnos tic inform ation is r ec om m ended:
The rec eiv ed telegram c an then be viewed, char ac ter for c har ac ter in an index ed diagnos tics par am eter field.
Additional, 16-bit diagnostic par am eters :
1. Inter face hardwar e v er s ion
2. Inter face soft war e r eleas e
3. Reserve
4. One 16-bit wor d for t he er r or s tat us
Bits 15 to 8: r es er v ed for us e later
Bit 7: Mast er : Respons e delay time ex pir ed
Slave: Monit oring time for cyclic t elegrams, set at the user level, expired
Bit 6: Incor r ec t t elegr am length (LGE)
Bit 5: Residual telegr am r un time ex pir ed
Bit 4: I ncorrect
block chec k c har ac ter
(BCC)
Bit 3: Telegram s tart not identif ied ( firs t char ac ter, no ST X )
Bit 2: Parity error
Bit 1: Buffer ov er flow
Bit 0: Charact er fram e er r or
5. Number of telegrams r ec eiv ed er r or - free per m inute
6. Number of r ejec ted telegr am s per m inute
7. Counter: Error-free telegrams
8. Counter: Rejected telegram s
9. Counter: Charact er fram e er r or
10. Counter: Overflow error
11. Counter: Parity error
12. Counter : Telegram s tart not identif ied
13. Counter : Telegram r es idual r un time ex pir ed
14. Counter: BCC error
15. Counter : Incorr ec t t elegr am length
16. Counter : Monitoring time ex pir ed
Additional c ounters and fields c an be pr ov ided.
A: Protocol specification
Specification, USS protocol A - 11
E20125-D0001-S302-A1-7600
5.3. Mirror teleg ram
The mas ter c an r eques t a so- c alled m ir r or telegram from the slav e.
The sequenc e is then as follows:
The mas ter s ends a telegram to t he appr opr iate slav e node. T his telegram is differ ent f r om the norm al telegram
in the f act that bit No. 6 of the address byte is set (=log. 1). T he slave sends (mirrors) t his telegram directly
back t o the mas ter without m ak ing any c hanges . I n this c as e, t he c onditions spec ified in Sec tion 5. 1 ar e v alid.
Data t r ans fer between t he m as ter and s lav e c an be c hec k ed us ing the mir r or telegram . T his is beneficial during
step-by-st ep st art-up or t r oubleshoot ing.
5.3. 1. Special t eleg ram
The USS prot oc ol c an als o be us ed for spec ial applic ations, which r equir e a net dat a s truc ture diff er ent fr om
that s pec ified in t he c onv er ter pr ofile (r efer to Sec tion C).
In order to perm it mix ed oper ation including applic ations with conv er ter pr ofile and special applic ations on one
bus with a m as ter, t hes e s pec ial telegram s m us t be uniquely identif iable in or der to be rejec ted by slav es with
converter pr ofile.
The struc ture of t he s pec ial telegram fram e c or r es ponds c om pletely to all other telegram s ( S TX, LG E , ADR, net
data, B CC, max . net data lengt h = 252 bytes) .
The nodes with spec ial telegram handling ar e addr es s ed as defined under 4.3 (as s igning addr es s by te (A DR) ) .
An address ( bits 0 to 4) m us t be unique on t he bus . T his m eans , t hat a node wit h s pec ial telegram handling,
can be address ed both wit h s tandard telegram s ac c or ding to t he c onv er ter pr ofile (bit 7= 0) as well as s pec ial
application ( bit 7=1).
A broadcas t, whic h is only addr es s ed to nodes with spec ial telegram handling, is pos s ible us ing the broadc as t
bit (bit 5).
Bus nodes, which c annot handle spec ial telegram s ( bit 7= 1) , mus t not be able to res pond to norm al telegrams
(bit 7=0) .
A mirr or telegram is only pos s ible with bit 7=0.
Bit
7Bit
6Bit
5 Significance
100
Special t elegr am : T he telegram is r ec eiv ed and r es ponded to by the nodes
addressed with bit s 0 to 4 (nodes with spec ial telegram pr oc es s ing c apability) .
101
Special t elegr am with broadc as t: The node number is not evaluated. A ll nodes with
special t elegr am pr oc es s ing c apability r ec eiv e the t elegr am , but do not send a
response telegram bac k to t he m as ter.
0 x x Refer to 4. 3
Table 5.2: Truth table of possible combinations of bits 5, 6 and 7 in the address byte (ADR) for special telegrams (bit 7=log. 1)
It is n ot permi ssible that non-defined combinations resul t in a respo nse.
A: Protocol specification
A - 12 Specification, USS protocol
E20125-D0001-S302-A1-7600
6. Definitions
6.1. Character run t ime
The char ac ter r un time is the t im e r equir ed to t r ans fer a c har ac ter ( 11- bit charac ter fram e) . T his time is a
function of the baud rate.
tz 11 1000
transfer rate ms
=•
6.2. Comp ressed teleg ram residual run time
The com pr es s ed telegram r es idual r un time is defined as the run time whic h is r equir ed in or der to
consecutively trans m it LG E , ADR, n net c har ac ters and B CC as a bloc k ( i. e. the stop bit of a char ac ter is
immediat ely followed by the start bit of t he nex t char ac ter).
The com pr es s ed telegram r es idual r un time is thus obtained as follows:
(n + 3) * c har ac ter r un time.
6.3. Maximum teleg ram residual run time
The max im um telegram r es idual r un time, includes , as illus trated in F ig. 6.1, in addit ion to t he c om pr es s ed
telegram r es idual r un time, char ac ter delay times . T he s um of t he c har ac ter delay times is equal to 50 % of the
compres s ed telegram r es idual r un time.
The max im um telegram r es idual r un time is thus obtained as follows:
1.5 * com pr es s ed telegram r es idual r un time
corres ponding to:
1.5 * (n + 3) * c har ac ter run time
STX LGE ADR 1.
Compressed tele
g
ram
2. n BCC
residual run time 50 % of the compressed
telegram residual run time
STX LGE ADR 1. 2. n BCC
max. telegram residual run time
Character delay time
Fig. 6.1: Telegram residual run time
The delay time between t wo c har ac ters ( = char ac ter delay time) m us t be less than t he s tart delay ( interv al) and
can be dist r ibuted as r equir ed between t he c har ac ters . I t is not neces s ar y to monit or the char ac ter delay time.
B: Physical interface and bus structure
Specification, USS protocol B - 1
E20125-D0001-S302-A1-7600
B: Physical interface and bus structure
The dat a transf er medium and the physical bus interface are essentially defined by t he bus syst em application.
It is pos s ible to use v ar ious phy s ic al interfaces for the USS pr otocol. However , when selec ting the phy s ic al
interface for a par ticular applic ation, the requir ed data t r ans fer sec ur ity and r eliability s hould be noted.
The basis for the USS pr otocol phy s ic al interface is the "r ec om m ended s tandard RS - 485 ac c or ding to / 2/.
For point-to-point connec tions, a sub- quantit y of EI A RS - 232 ( CCITT V.24), TTY (20 mA current loop) or f iber -
optic c able c an be us ed as phy s ic al interface.
This section describes how a USS f iel d b us mu st be structured in ord er t o g uaran t ee reli abl e data
transport by the data transfer medium in standard applications. For special application conditions,
other eff ect s must be taken i nto account, which would require additional measures or rest rictions,
which are no t handled in this specification.
1. Topology
The USS bus is bas ed on a line topology wit hout drop lines .
Both ends of t he line term inate at a node.
The max im um c able length, and thus the max im um dis tance between t he m as ter and the last s lav e is lim ited by
the cable c har ac teris tics , ambient conditions and data t r ans fer rate. For a data t r ans fer r ate < 100 k bit/ s , a
maximum length of 1200 m is pos s ible. (E IA s tandard RS - 422- a, Decem ber 1978, Appendix , Page 14)
The max im um num ber of nodes is lim ited t o 32 ( 1 m as ter, 31 slav es ) .
"Slave"
max. 31
Slaves
Last nodeFirst node
"Master"
"Slave" "Slave"
Fig. 1.1: Topology, USS
bus
Point- to-point connec tions ar e treated just like bus c onnec tions. One node has the mas ter function and t he
other the slav e function.
B: Physical interface and bus structure
B - 2 Specification, USS protocol
E20125-D0001-S302-A1-7600
2. Data transfer technology
Data t r ans fer is r ealiz ed ac c or ding to t he E IA 485 S tandard ( /2/ ) .
RS232 or T TY c an be us ed for point-to-point couplings .
Data t r ans fer is alway s half-duplex , i. e. sending and r ec eiv ing ar e alternately r ealiz ed and m us t be cont r olled
by the s oft war e. T he half-duplex technique allows the sam e c ables to be used for bot h data t r ans fer dir ec tions.
This per m its s im ple and favor ably - pr ic ed bus c abling, operation in noisy env ir onm ents and a high data t r ans fer
rate.
2.1. Cable characteristics
Screened, t wis ted t wo- c or e c onduc tor c ables ar e us ed for the bus c able.
Note:
All of this inform ation is only a r ec om m endation. Ot her m eas ur es or r es tric tions may be r equir ed depending on
the actual requir em ents and applic ation and conditions on s ite.
Structure:
Conductor cross-section: 2 x ≈ 0.5 mm ²
Conductor: ≥ 16 x ≤ 0.2 m m
Twisting: ≥ 20 twists / m
Overall screening: braided, t inned copper wire, diameter ≥ 1. 1 m m ²
85 % optical c ov er age
Over all diam eter: ≥ 5 mm
Ext er nal s heath: depending on the requir em ents r egar ding flamm ability, debris r em aining aft er
burning, etc.
Th ermal/ electrical characteristics:
Conductor r es is tance ( 20°C): ≤ 40 Ω/km
Insulation res is tance ( 20°C): ≥ 200 MΩ/km
Operating voltage (20°C): ≥ 300V
Test voltage (20°C): ≥ 1500V
Temper ature r ange: -40C ≤ T ≥ 80°C
Load capability : ≥ 5A
Capacitance: ≤ 120 pF /m
Mechani cal ch aract eristics:
Single bending: ≤ 5 x external diam eter
Repeated bending: ≤ 20 x external diam eter
Recommendations:
1. Standard, wit hout any s pec ial r equir em ents:
Two-core, flexible, screened conductor in accordance with VDE 0812 with colored PVC sheat h.
PVC insulation, r es is tant to oil and pet r oleum pr oduc ts.
Type: LIYCY 2 x 0.5 mm ²
For ex am ple: M etrofunk Kabel- Union GmbH 12111 B er lin P os tf ac h 41 01 09
Tel 030-831 40 52, F ax : 030-792 53 43
2. Halogen-free c ables ( no gas eous hy dr oc hlor ic ac id when bur ning) :
Halogen-fr ee, highly flexible c ables , res is tant to high t em per atures and c old. Sheat h m anufactured from an A S S
special mix ture with a silic on bas is :
Type: ASS 1 x 2 x 0.5 mm²
From : Metr ofunk K abel- Union GmbH 12111 B er lin P os tf ac h 41 01 09
Tel 030-831 40 52, F ax : 030-792 53 43
B: Physical interface and bus structure
Specification, USS protocol B - 3
E20125-D0001-S302-A1-7600
3. Recom m ended, if halogen- and s ilic on- free c ables ar e r equir ed:
Type: BET A flam G-M /G - G-B 1 flex 2 x 0.5 mm ²
From : . Studer- K abel- A G, CH 4658 Dänik en
B: Physical interface and bus structure
B - 4 Specification, USS protocol
E20125-D0001-S302-A1-7600
2.2. Cable length
The cable length is dependent on t he data t r ans m is s ion r ate and t he num ber of connec ted nodes. The following
cable length ar e pos s ible under the cable s pec ifications, spec ified in 2. 1:
Data transfer rate Max. node number Max. cable length
9.6 kbit/ s 32 1200 m
19.2 kbit/ s 32 1200 m
38.4 kbit/ s 32 1200 m
187.5 kbit/ s 30 1000 m
Table 2.1: Cable lengths as a function of the data transmission rate
2.3. Interface characteristics
The f ollowing text disc us s es how the phys ic al interface is im plem ented acc or ding to EI A RS 485.
The int er face c an be c onfigured, eit her non- float ing or float ing with res pec t to the int er nal elec tronic s per s upply
voltage.
The bus can be conf igured using only two-core cables as a result of t he mast er-slave bus access technique.
This r equir es , t hat at any par ticular time, only one s ender c an ac c es s the bus. All ot her nodes m us t switch the
senders to a high-ohm ic s tat e ( " m onitoring" ) .
The logical 0- and 1- s tat us es for RS 485 technology ar e identif ied by the polarity of the v oltage dif ferenc e
between t he two dat a lines .
The EIA RS - 485 and E IA RS - 422 S tandards ar e ex c lus iv ely v alid for the char ac teris tics of t he s end- and
receive blocks. T he values t aken from t hese st andard, are characteristic values, as to how the correct signal
shape can be t es ted on an installed bus.
A sender m us t generate, under test conditions and ac c or ding to RS- 485 S tandard (the bus is term inated wit h 54
Ω), a s pec ific v oltage dif ferenc e Vo between t he RS 485P and RS 485N s ignal lines :
Logical 1 st atus: 1.5 V ≤ Vo ≤5 V RS485P is pos itive with respec t t o RS 485N
Logical 0 st atus: -5 V ≤ Vo ≤-1.5 V RS485P is negative with res pec t t o RS 485N
The rate of r is e and r ate of fall t im es , i. e. t he time to change bet ween two logical s tat us es m us t not ex c eed, on
the bus:
0.3 / data t r ans fer r ate
If none of t he nodes s ends , t he v oltage dif ferenc e is defined t o be a pos itive lev el by the basis network ( r efer to
Sect ion 4.5, B us term ination).
Data t r ans fer is as y nc hr onous .
The deviation of the rec eiv e- and s end c loc k from the nominal v alue is a m ax im um of ± 0.3%.
The t elegr am c har ac ters ar e s ent and rec eiv ed as bit-s er ial UA RT char ac ters .
The t im e between t he s top bit of a char ac ter and the start bit of t he nex t char ac ter within a t elegr am m us t be
less t han two char ac ter r un times .
B: Physical interface and bus structure
Specification, USS protocol B - 5
E20125-D0001-S302-A1-7600
2.4. Data transfer rate
The f ollowing data t r ans fer r ates ar e us ed for the USS interface:
300 bit / s
600 bit / s
1200 bit / s :
2400 bit / s
4800 bit / s
9600 bi t / s
19200 bi t / s
38400 bi t / s
57600 bit / s
76800 bit / s
93750 bit / s
115200 bit / s
187500 bi t / s
The dat a trans fer r ates whic h ar e highlighted are r ec om m ended for US S, and s hould be im plem ented on all
interfaces.
B: Physical interface and bus structure
B - 6 Specification, USS protocol
E20125-D0001-S302-A1-7600
3. Data transfer techniques
The usual UART blocks are used for the serial asynchronous data tr ansfer, as is generally used for digital data
transfer.
3.1. Bit coding
The char ac ters ar e trans ferr ed, as they ar e c oded from the UART bloc k . T he c ode is des ignated as non- r eturn
to-z er o c ode ( NRZ code) . A bit cons is ts of a squar e wav e puls e, whose width corr es ponds to t he c loc k ( 1/dat a
transfer rate).
Clock
NRZ code 101001100
Fig. 3.1: NRZ code
3.2. Character frames
Each t r ans ferr ed c har ac ter s tarts with a start bit and ends with a stop bit . 8 dat a bits ar e trans ferr ed. Each
character ( by te) has a par ity bit (ev en par ity, i. e. the num ber of logical ones in the dat a bits, including the parity
bit, is an ev en num ber ) . An er r or m es s age is gener ated if the char ac ter fram e is not maintained (refer to F ig.
3.1).
Start-
bit 213
4
57
MSB
6even
Parity Stop-
bit
1
0t
D a ta b its
11- bit character frame
Start-
bit
Time between two characters
(
less than 2 x the character ru n time
)
C harac ter run time
0
LSB
Fig. 3.2: Character frame
The start bit is alway s a logic al 0, t he 8 data bit s c an hav e any bit pat tern, the par ity bit is either 1 or 0 and the
stop bit is alway s a logic al 1. T he s ignal lev el r em ains a logic al 0 up to t he s tart bit of t he nex t charac ter in the
same t elegr am .
LSB is the least significant bit and MSB t he most significant bit .
B: Physical interface and bus structure
Specification, USS protocol B - 7
E20125-D0001-S302-A1-7600
4. Configuration guidelines
4.1. Cable routing
When r outing the US S bus cable, it should be ensured t hat t he syst em is configured in accordance wit h EMC
guidelines. The f ollowing points s hould be s pec ially obs er v ed:
•The bus c able m ay be r outed in one bundle or c able duc t wit h other dat a c ables ( P G, pr inter, SINEC
L2-DP), unsc r eened c ables for DC v oltages ≤ 60 V and unscreened cables for AC voltages ≤ 25 V.
•The bus cable may not be routed together wit h unscreened cables for DC voltages > 60 V and ≤ 400
V together in a bundle or c able duc t.
•A minimum clearance of 10 cm must be maintained bet ween the bus cable and unscreened cables for
AC volt ages > 25 V and ≤ 400 V .
•A minimum c lear anc e of 50 cm m us t be maintained bet ween the USS bus c able and data net wor k
cables (e. g. S INEC H1) .
•A minimum c lear anc e of 1m m us t be maintained t o nois e s our c es ( trans form er s , contact or s , motors ,
electr ic al welding equipm ent).
•The cables m us t be routed t hr ough the shor test poss ible path bet ween 2 nodes .
•Potential bonding cables and s ignal c ables s hould be r outed as c los e toget her as pos s ible.
•Cable extens ions v ia term inals or c onnec tors m us t be avoided.
•Cables should be routed clos e to grounded s ur faces .
4.2. Potential bonding
If bus nodes ar e c onnec ted t hr ough non- float ing interfaces , or if nodes ar e gr ounded at different plant s ec tions,
or if the dif ferenc e between t he 0 V potent ials of t he interface electronic s ≥ 7 V, dat a trans fer c ould be dis turbed
and the boards c ould be dam aged.
In all ot her c as es , pot ential bonding should be r ealiz ed between t he c onv er ter gr ound potent ials .
Cross s ec tion of the copper potent ial bonding c able:
• 16 mm² for cable lengt hs up t o 200 m
• 25 mm² for cable lengths above 200 m
The pot ential bonding cable s hould be c onnec ted, for all nodes , t o gr ound through the larges t possible s ur face
area.
(also refer to F ig. 4. 2: Sc r eening and potent ial bonding)
4.3. Screening
Screening dam ps m agnetic, electric al and elec trom agnetic nois e fields. Noise cur r ents ar e fed t o gr ound
through t he screen braiding and the housing ground.
•The screens of all nodes should be connected to the housing ground/ground (grounded screen bar)
through the larges t sur face ar ea.
•If there is no potential bonding (only in except ional cases), then t he screen may only be connect ed at
one end.
•The sc r een s hould be c onnec ted wit h the metallic c onnec tor hous ing.
•The connec tor hous ing in the int er face elec tronic s m us t not be in c ontact with the housing /
electronics power supply ground (otherwise, do not connect t he screen with t he connect or housing).
•It is not permissible to connect the screen through a pin (e. g. pin 1), as otherwise the noise currents
would be fed t o gr ound through the int er face elec tronic s ( the int er face elec tronics would be
destroyed).
(also refer to F ig. 4. 2: Sc r eening and potent ial bonding)
B: Physical interface and bus structure
B - 8 Specification, USS protocol
E20125-D0001-S302-A1-7600
4.4. Termination technology, connector assignments
The connec tor / t er m inal des ign and as s ignm ent is not spec ified. E ac h indiv idual c as e s hould be ev aluated
(space r equir em ent, ac c es s ibility etc.. ) . However , it is r ec om m ended that, if at all poss ible, SINEC L2- DP
term ination t ec hnology is us ed.
Pin assi gn ment of t he b us i nterface wi t h 9-pin SUB-D connector:
Socket connec tors ar e pr ov ided on the int er face s ide and plug c onnec tors on the cable s ide.
PIN 1 - Free
PIN 2 - Free
PIN 3 RS485P Receiv e- and trans m it signal ( +)
PIN 4 (-) Reserve (for SINEC L2-DP direction signals for repeater s)
PIN 5 0 V Data referenc e potent ial
PIN 6 5 V Power supply voltage
PIN 7 - Free
PIN 8 RS485N Receive- and trans m it signal (- )
PIN 9 (-) Reserve (for SINEC L2-DP direction signals for repeater s)
Assig nmen t of t he b us i nterf ace f or terminal connection:
Term inal 1 RS485P Connection cable 1, positive signal lev el
Term inal 2 RS485N Connect ion c able 1, negat iv e s ignal lev el
Term inal 3 RS485P Connection cable 2, positive signal lev el
Term inal 4 RS485P Connection cable 2, negat iv e s ignal lev el
Term inal 5 0Vext
Term inal 6 5Vext optional, is only r equir ed for an ex ternal bas is network
Termi nal 1 and t ermin al 2 are i nternal ly conn ect ed;
Termi nal 2 and t ermin al 4 are i nternal ly conn ect ed
Cable 1: Cable to the prev ious node on the bus
Cable 2: Cable to the f ollowing node on the bus
If it is not permis s ible that the bus is interr upted if the connec tor is withdrawn from the int er face, t hen c or e
RS485P f r om c able 1 and 2 m us t be connec ted under term inal 1 and c or es RS 485N from c able 1 and 2, under
term inal 2.
B: Physical interface and bus structure
Specification, USS protocol B - 9
E20125-D0001-S302-A1-7600
4.5. Bus termin at io n
The bus c able m us t be t er m inated at both ends.
A 150 Ω resis tor m us t be connec ted bet ween data signal lines RS 485P and RS 485N at the firs t and last node.
The bus term inating res is tor on the int er face boar d c an be ac tivated with the jumper s ett ings . T he bus
term inating res is tor is not activated when t he boar d is s upplied.
If the bus term inating res is tor c annot be mounted on t he interf ac e boar d, t hen it mus t be mounted in a
connect or hous ing.
Basis n et wo rk
If none of t he nodes trans m its, t hen the bus is at an undef ined potential, becaus e all trans m itt er s ar e s witched
to a high-ohm ic c ondition. To suppr es s s ignal nois e in this s tat us , t he bus has a bas is network , so t hat a
defined positive s ignal lev el is obtained. The basis network s hould be c onnec ted at both nodes at which t he bus
is ter m inated.
The location of the basis network r es is tors is the sam e as for the bus t er m inating res is tor.
Bus terminatin
g
re sis to r
Resistor
w. r. t. suppl
y
volta
g
e
390
390 150
Resistor
w. r. t. si
g
nal ref.
+ 5 V
0 V
RS485N
RS485P
RS485
Fig. 4.1: Basis network and bus termination
390 Ω res is tors ar e r ec om m ended if t he interf ac e s upply v oltage is 5 V ( for 15 V , approx . 1 kΩ with r es pec t t o
the supply v oltage and 390 Ω with r es pec t t o 0 V ) .
The int er face m us t prov ide the power s upply v oltage at a pin or term inal. T he v oltage sourc e m us t be able t o
drive a 10 mA s hor t-c ir c uit cur r ent.
B: Physical interface and bus structure
B - 10 Specification, USS protocol
E20125-D0001-S302-A1-7600
D ata line
0 V Si
g
na l level,
external
Housin
g
g
round,
screen bar
Potential bondin
g
Screen
Bu s te rmination
an d basis network
Fig. 4.2: Screening and potential bonding
B: Physical interface and bus structure
Specification, USS protocol B - 11
E20125-D0001-S302-A1-7600
4.6. Recommen ded circu it
A recom m ended c ir c uit f or a float ing US S inter face is s hown in the following diagr am , whose c onnec tions ar e
fed t o term inals :
+5 V
150 mA
390
100k
100k 390
BR1
BR2 150
Screen bar
Non-floatin
g
or
floatin
g
desi
g
n
BR 1 and BR 2 are closed for bus termination; open w hen supplied.
Electrical isolation is optional.
2
3
4
1
5
TxD
RxD
0 V
56
µ
H
10nF
470pF
RS485
RS485P
RS485N
MextRS485
470pF
RS485N
RS485P
1M
22nF 1M
22nF
optional
Fig. 4.3: EIA RS485 interface structure, 2-wire, floating
C: Defining the net data
Specification USS protocol C - 1
E20125-D0001-S302-A1-7600
C: Defining the net data for drive applications
1. Introduction
The USS prot oc ol allows the user to configure a s er ial bus c oupling between a high-lev el m as ter and s ev er al
slave systems. Master systems can, for example, be PLCs or PCs. The SI MOVERT and SIMOREG drives are
always slav es on the bus.
The USS protocol allows t he user to implement automat ion t asks requiring a cyclic (time) telegram transfer
(fixed t elegram length required), is well as visualization t asks. In this case, t he variable t elegram length prot ocol
is advantageous, as texts and parameter descriptions can be transf erred with one t elegram wit hout breaking up
the inf or m ation.
However, drive automation tasks (open-loop and closed-loop cont rol), require cyclic telegram t r ansf er, which
can only be realiz ed if t he telegram s ar e a fixed length. The selec ted t elegr am length may not be changed
during operat ion. A fixed telegram length limits the number of charac ters in the t elegr am net dat a bloc k .
The subsequent section describes, in detail, t he stru ct ure o f t he n et data bl ocks co ntained i n the teleg ram
as well as t he nec es s ar y s ett ings ( par am eteriz ation) of t he interface, thr ough whic h data t r ans fer is to be
realized. Com m unic ations c an be r ealiz ed through a bas ic c onv er ter interface or through a s epar ate inter face
board.
The struc ture of t he net dat a bloc k in the t elegr am is independent of the specification of the protocol with which
the net data is trans ferr ed. T he s truc ture inc luding the cont ents of t he net dat a es s entially c or r es pond to t he
definit ions f or cyclic data tr ansf er via PROFIBUS (PROFIBUS profile " v ar iable- s peed dr iv es " /1/ ) . Thus , t he
user is guar anteed, that he c an ac c es s the proc es s data (= control / stat us wor ds and s etpoint / actual values )
with t he same access mechanisms, independent as whether t his is realized using USS or PROFIBUS-
DP/FMS.
The subsequent descriptions are independent of any part icular convert er and are intended to provide the user
with guidelines as to how t he US S protocol is t o be handled. Documentat ion of t he US S pr otocol for the
individual conver ters s hould be c r eated f or a s pec ific c onv er ter applic ation. This applic ation should cov er how
the bus is to be struc tured and how the protocol is to be param eterized; f ur ther, it s hould be defined which net
data content s the conv er ter „ under s tands“ .
The specification must be observed for al l i mpl emented systems.
C: Defining the net data
C - 2 Specification USS protocol
E20125-D0001-S302-A1-7600
2. General structure of the net data block
The net data block is s ubdiv ided into t wo ar eas , t he
• P K W (par am eter ID value) ar ea and the
• PZ D (process data) area
• The
PKW area ref ers t o t he handling of t he paramet er ID value (PKW) interface. The PKW int erface
does not inv olv e a phy s ic al interface, but defines a m ec hanis m whic h handles par am eter trans fer
between t wo c om m unic ation partners . T his m eans , reading and wr iting param eter v alues , parameter
definit ions and as s oc iated t ex ts as well as handling par am eter c hanges us ing par am eter c hange
reports. All tasks, which are realized through the PKW int erface, are operator cont rol and visualization
tasks, service and diagnost ics.
• The
PZD area c ontains the signals r equir ed for the automation:
Control word (s) and set point (s) from t he master to t he slave
Stat us word (s) and act ual value (s) from t he slave to the mast er.
The net data block is c r eated f r om the com bination of both areas . T his s tructure is v alid for the task tel egram
(master → slave) as well as for the resp on se t elegram ( s lav e → master).
PZD area
variable length variable length
PKW area
PKW elementsINDPKE PZDnPZD1
Fig. 2.1: Net data block
A task teleg ram is the tr ans fer of a com plete net data block from the mas ter t o the slav e.
A response teleg ram is the tr ans fer of t he c om plete net data block from the slav e to the m as ter.
C: Defining the net data
Specification USS protocol C - 3
E20125-D0001-S302-A1-7600
PKW area:
Using so-called "tasks" and " responses" , in this area, access to the parameters accessible in a converter and
via a USS interface ar e c ov er ed.
PKE = Paramet er ID (PKE); is used t o identify and initiate tasks and responses for processing
paramet er s and is alway s one word long ( ^ 16 bit s ) . T he par am eter num ber is also
contained in t he PKE.
IND = The index is always one word long. The signif icance of the index is described in det ail in
Sect ion 4.2. 2.
PW E elem ent = Infor m ation, as s oc iated wit h a task or a r es pons e ( defined in t he P K WE) s uc h as par am eter
values, t ext s or parameter description data are tr ansf erred. This area can vary in length
depending on the t as k /res pons e. I f only P ZD dat a ar e to be t r ans ferr ed in the net data block ,
the number of PKW elements can be set t o 0 (PKE + index + PW E elements)!
PZD area:
Proces s data are continuously trans ferred between t he m as ter and s lav es in this ar ea. At t he s tart of
communic ations, it is c onfigured as to which pr oc es s data are ex c hanged with a slav e. For ex am ple, t he c ur r ent
setpoint is trans ferr ed to slav e x in the sec ond P ZD (= PZD 2). This s ett ing r em ains for the com plete dat a
transfer.
PZD1-PZ Dn = Process data (= control / status word (s) and setpoint(s) / actual value (s));
the cont rol / stat us word (s), setpoint s and act ual values required for the automat ion are
trans ferr ed in this ar ea.
The lengt h of t he P ZD area is defined by the number of PZD elements and t heir s iz e ( e. g.
word, double wor d) . Cont r ar y to t he P K W area, which c an be v ar iable, t he length of this ar ea
must alway s be per m anently agr eed upon between t he c om m unic ation partners ! T he
maximum num ber of PZD words per telegram is lim ited t o 16 wor ds . I f only P K W dat a ar e to
be trans ferr ed in the net data block , t hen the number of PZD can also be 0!
Depending on the dat a trans m is s ion dir ec tion, the control wor d or the stat us wor d is alway s
trans m itt ed in P ZD1. The main s etpoint or the main ac tual value is alway s transm itt ed in
PZD2, cor r es ponding to t he data t r ans m is s ion dir ec tion. A dditional setpoint s and ac tual
values or c ontrol / stat us wor ds ar e s ent in t he following proc es s data PZD 3 to P ZD n.
The lengt h of t he indiv idual ar eas m us t be negot iated bet ween the com m unic ation partners , ref er to Sec tion 7.
For this pur pos e, var ious par am eters s hould be pr ov ided in the basic c onv er ter with which the PKW and PZD
component s for the protocol at t he s er ial interfaces c an be s et.
C: Defining the net data
C - 4 Specification USS protocol
E20125-D0001-S302-A1-7600
3. Parameterization of the USS protocol at a serial interface
Every s er ial interface, on which the USS protoc ol is to be implem ented, m us t have, in edit ion to param eters
for the bus addr es s , baud rate and t elegr am failure time, t wo par am eters with which the lengt h of t he P K W- and
PZD ar eas c an be independently s et. The appropr iate int er face c an either be pr ov ided at the bas ic c onv er ter or
on a communic ations boar d. T he latt er option requir es an appr opr iate mec hanis m , so that the requir ed
paramet er iz ation can be m ade on the com m unic ations boar d. F or ex am ple, t he r elev ant param eters c an be
trans ferr ed from the basic c onv er ter to t he c om m unic ations boar d v ia a dual por t RAM c oupling.
3.1. Parameter sett ing for 6SE21, 6SE30 (Micro Master) SIMOVERT converters and
SIM OREG K 6RA24
Baud rat e
PNU: Converter-specific →Parameter num ber ( P NU) , e. g. P783 for
SIM OREG K 6RA 24
Designator: Converter-specific →Is us ed for a plain text display on the
operator c ontrol panel ( e. g. baud r ate)
Type: 02 →Data type: refer to /1/
Function: Baud rat e
Parameter v alue
(PWE)
1 ^ 300 Baud
2 ^ 600 Baud
3 ^ 1200 Baud
4 ^ 2400 Baud
5 ^ 4800 Baud
6 ^ 9600 Baud
7 ^ 19200 Baud
8 ^ 38400 Baud
9 ^ 93750 Baud
10 ^187500 B aud
Note: S pec ial baud r ates, beyond these ar e s toreed at > 20!
C: Defining the net data
Specification USS protocol C - 5
E20125-D0001-S302-A1-7600
Bus ad dress
PNU: Converter-specific
Designator: Converter-specific →e. g. BUS_ADR
Type: O2
Function: Bus addr es s
PWE: 0 - 31
Tel egram fail ure time
In order to monitor the t im e taken by the mas ter to address the slav e on the basic c onv er ter, t he m ax im um time
between t wo v alid telegram s addr es s ed to t he bas ic c onv er ter s hould be par am eteriz ed us ing this par am eter.
The t im e units us ed ar e "seconds " (sec ) . T he par am eter s hould be s et t o 0 if monitoring is not requir ed.
PNU: Converter-specific
Designator: Converter-specific →e. g. TLG_AUS
Type: O2
Function: T elegr am failure time in
seconds for the basic
converter interface.
PWE: 0 - 32
(0 : No m onitoring)
(1 : Factory s ett ing)
Note:
The slav e time m onitoring only s tarts aft er its power s upply has been s witched-on and aft er the f ir s t f ault-free
task telegram has been r ec eiv ed.
C: Defining the net data
C - 6 Specification USS protocol
E20125-D0001-S302-A1-7600
Numb er of P KW el ements
The number of PK W elements in the PK W area of t he net dat a bloc k is defined per par am eter. The spec ification
always refers to PK W elements in the single- wor d form at.
PNU: Converter-specific
Designator: Converter-specific →e. g. P K W_ANZ
Type: O2
Function: PKW num ber
PWE: 0 →0 wor ds
3 →const ant, 3 wor ds
4 →const ant, 4 wor ds
127 →variable lengt h
Caution:
If only telegram s with cons tant net dat a quantit ies ar e to be used, 126 must not be ex c eeded when the number
of PKW and number of PZD are added. According t o t he USS - pr otocol s pec ification, a m ax im um of 252 bytes
(126 words) is permitt ed. If telegrams with variable PKW component s are used, these parameters (PKW_ANZ )
must be s et t o 127, independent of param eter P ZD_ANZ.
Numb er of P ZD el ements
The quant ity of proc es s data contained in t he net dat a bloc k c an be influenced us ing this param eter. T he
specif ic ation always r efers to a PZD element in t he s ingle- wor d form at.
PNU: Converter-specific
Designator: Converter-specific →e. g. P ZD_ANZ
Type: O2
Function: PZD number
PW E : 0 - 16 ( wor ds )
C: Defining the net data
Specification USS protocol C - 7
E20125-D0001-S302-A1-7600
3.2. Parameter sett ing for SIMOVERT Master Drives
Contrar y to t he pr ev ious par am eter definit ions the param eter, baud rate, bus addr es s , PK W_ANZ and PZD
_ANZ par am eter, are the "ar r ay " data t y pe with index 1 to 3 f or the particular US S protocol on the basic
converter S S T1, or S S T2 on t he S CB boar d (Serial Comm unic ations Board).
PNU: P683
Designator : S S T/ S CB bus addr es s
Type: Array, data type 02 →Data t y pe: Ref er to / 1/
Function:
Bus addres s for US S at t he interface on the basic
converter and on the SCB c om m unic ations boar d
Index Parameter v alue ( P WE)
1 ^ SST 1
2 ^ SCB
3 ^ SST 2
0 to 30
PNU: P684
Designator : S S T/ S CB baud r ate
Type: Array, data type 02 →Data t y pe: Ref er to / 1/
Function:
Baud rat e for US S at t he interface on the basic
converter and on the SCB c om m unic ations boar d
Index Parameter v alue ( P WE)
1 ^ SST 1
2 ^ SCB
3 ^ SST 2
1 ^ 300 baud
2 ^ 600 baud
3 ^ 1200 baud
4 ^ 2400 baud
5 ^ 4800 baud
6 ^ 9600 baud
7 ^ 19200 baud
8 ^ 38400 baud
Example: T he 38.4 kbit/ s baud r ate at
interface 1 of t he bas ic c onv er ter is s et t o
paramet er v alue = 8 by s etting par am eter
P684 with index = 1.
C: Defining the net data
C - 8 Specification USS protocol
E20125-D0001-S302-A1-7600
PNU: P685
Designator : S S T/ S CB P K W number
Type: Array, data type 02 →Data t y pe: Ref er to / 1/
Function:
Number of wor ds ( 16 bit) in the PK W area in the net data
block at the int er faces on the basic c onv er ter and on the
SCB com m unic ations boar ds
Index Parameter v alue ( P WE)
1 ^ SST 1
2 ^ SCB
3 ^ SST 2
0 →0 words
3 → const ant, 3 wor ds
4 → const ant, 4 wor ds
127 →variable lengt h
PNU: P686
Designator : S S T/ S CB P ZD number
Type: Array, data type 02 →Data t y pe: Ref er to / 1/
Function:
Number of wor ds ( 16 bit) in the PZD area of t he us eful
data area at t he interfaces of t he bas ic c onv er ter and on
the SCB c om m unic ation boards
Index Parameter v alue ( P WE)
1 ^ SST 1
2 ^ SCB
3 ^ SST 2
0 to 16
C: Defining the net data
Specification USS protocol C - 9
E20125-D0001-S302-A1-7600
PNU: P687
Designator : S Com /SCB Tlg of f
Type: Array, with data type 02 →Data ty pe: Ref er to /1/
Function:
Telegram failure time for US S at t he interfaces of t he
basic conv er ter and the SCB c om m unic ations boar ds
Index Parameter v alue ( P WE)
1 ^ SST 1
2 ^ SCB
3 ^ SST 2
0 to 6500 [ m s ]
C: Defining the net data
C - 10 Specification USS protocol
E20125-D0001-S302-A1-7600
4. PKW area
4.1. Stru ct ure o f t he PKW area (parameter ID val ue)
The struc ture of t he P K W area, is, as far as the sequence of it s elem ents is c onc er ned, always the sam e and
only differ from the standard s truc ture by the number of it s par am eter v alues ( P WE) .
The param eter ar ea c an be s et wit h either a fixed length (3 wor ds or 4 wor ds long) or with var iable length, v ia
paramet er P K W_ANZ, r efer to Sec tion 3. 1.
If there is no P K W area in the net data block , PKW_ANZ mu st be 0, whic h m eans that c onv er ter
parameterization is not possible via this interface!
4.1. 1. PKW area f or a fi xed teleg ram len gth
Standar d s truc ture for par am eter v alues in the single- wor d form at (16 bit ) :
Parameter ID Index Parameter
value 1
1 word
PKE IND PWE1
1 word 1 word
Fig. 4.1: Structure of the PKW area 3 words
If the PK W area is not set t o 0, refer to t he interf ac e par am eteriz ation, then t his ar ea m us t be 3 words long.
For a fixed telegram length, the number of words in the PK W area for bot h the t as k telegram ( m as ter to slav e)
as well as t he r es pons e telegram ( s lav e to mas ter) ar e alway s c ons tant and the sam e s iz e. F or
paramet er iz ation of the f ix ed P K W area, refer to Sec tion 3. 1; in this c as e, PK W_ANZ mus t be set t o 3.
Note:
It is nec es s ar y to def ine P K W_ANZ and PZD_ANZ f or a fixed telegram length, in or der to be able t o
paramet er iz e a c or r ec t and opt im um telegram m onitoring " telegram failure time" .
Standar d s truc ture for par am eter v alues as double- wor d form at (32 bit):
Parameter ID- Index
1 word 1 word 1 word 1 word
Parameter value (double word)
High word Low word
PKE IND PWE1 PW E 2
Parameter value (word)
0Parameter value
Fig. 4.2: Structure of the PKW area, 4 words
In t his c as e, if the PK W area is not param eteriz ed to 0, the number of words in the PK W area s hould be
paramet er iz ed to 4. This is v alid for both t he task as well as for the respons e telegram .
C: Defining the net data
Specification USS protocol C - 11
E20125-D0001-S302-A1-7600
4.1. 2. PKW area wit h vari abl e t eleg ram len gth
Standar d s truc ture:
PKE IND PWE1 PWE2 PWEm
Fig. 4.3: Structure of the PKW area, variable length
with: 1 word < m < 108 wor ds ( m ax im um ) , if there are 16 P ZD words ( m ax im um ) in the net data block .
1 word < m < 124 wor ds ( m ax im um ) , if there is no P ZD.
Telegram trans fer with var iable telegram length means that the slave r es ponds with a t elegr am in r es pons e to a
telegram from the mas ter; t he length of the t elegr am from the slav e no longer c oinc ides with t he length of the
task telegram from the mas ter.
The lengt h and as s ignm ent of elem ents P WE 1 to PWE m in the res pons e telegram ar e dependent on t he task
issued by the mas ter. Par am eter P K W_ANZ mus t be set to 127 in or der that the slav es c an r es pond
appropriately t o t asks which require a variable telegram lengt h.
The mas ter c an only ac c es s the slav e with a var iable telegram length when param eteriz ed for var iable telegram
length (PKW _ANZ = 127). Whereby, "v ariable" generally ref ers to a variable PKW area. T he PZ D-area length
must be t he same for task- and response t elegrams. In t his case, it must be checked as t o whet her the
telegram failure time s ett ing is pr ac tical.
4.2. Description of the individual PKW elements
4.2. 1. Parameter I D ( P KE )
PKE IND PWE
AK SP PNU
No.: 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Parameter No., Section 4.2.1.3
Bit for the parameter change report
(Section 4.2.1.2)
Task- and response ID (AK)
(Section 4.2.1.1)
Fig. 4.4: Parameter ID structure
4.2. 1.1. Task- and response ID
The t asks are issued, coded from t he mast er to the slave in the task I D (AK). The slave processes the task and
form ulates the appropr iate res pons e, which is then iss ued in c oded form ( r es pons e ID) t o the mas ter. T he task s
/ response I Ds are def ined so that a task and a response are clearly defined by t he PKE (AK + PNU), and f or
specific t asks / responses, additionally using the index word (IND).
Ta sk ID (master → slave)
Bit No.
15 14 13 12 Function Description
0000 No task No task for the PKW interface
0001 Request P WE Requests a par am eter v alue ( P WE)
0010 Change PW E ( wor d) Wr ites a param eter v alue, word form at (16 bit)
0011 Change PW E ( double wor d) Wr ites a param eter v alue, double-wor d form at (32 bit)
0100 Request PBE element 1) Reads an element f rom the parameter description (PBE).
IND def ines whic h elem ent is to read.
The complet e PBE is requested if IND = 255
0101 Change PBE element 1) Writ es an element f rom PBE; as for reading f r om PBE
0110 Request P WE ( ar r ay ) 1) Reads a parameter v alue from a one- dim ens ional field (^ ar r ay ) .
The position wit hin the f ield, f r om whic h the value is to be read, is c ontained in IND. F or ex am ple, I ND
= 4, t hen the PWE is trans ferr ed whic h is at t he 4th position in t he ar r ay .
0111 Change PW E ( ar r ay wor d) 1) Wr ites a value ( as wor d) to a spec ific pos ition in a one-dim ens ional field (ar r ay ) ; as for r eading.
1000 Change PW E ( ar r ay double wor d) 1) Wr ites a value as double wor d, suc h as ID 0111.
1001 Request the number of arr ay elem ents Reads the number of element s of a f ield.
1010 Reserve
1011 Change PW E ( ar r ay double wor d) , and st or e
in the EEPRO M 1), 2) Writes a parameter value (double word) to a position in an array into t he EEPROM
1100 Change PW E ( ar r ay wor d) , and st or e in the
EEPROM 1), 2) Writes a parameter value (word) at a specif ic posit ion in an array into t he EEPROM
1101 Change PW E ( double wor d) , and st or e in
EEPROM 2) Writes a parameter value (double word) into t he EEPRO M
1110 Change PW E ( wor d) , and st or e in the
EEPROM 2) Writes a parameter value (word) into t he EEPRO M .
1111 Request or c hange text 1), 2) 3) Reads or writes a text
1) For these tasks, to make them completely clear, the value is required, which is locat ed in IND in t he net data block, refer to Sec tion 4. 2.2.
2) These I Ds are only valid f or t he USS protocol. In the cyclic task IDs of the PROFIBUS profile /1/, thes e IDs ar e not available.
3) The " c hange text" s upplem ent is only v alid for S IMOVERT Mas ter Dr iv es
Table 4.1: Task IDs
Respo nse I Ds ( slave → master)
Bit No.
15 14 13 12 Function Description
0000 No response No response
0001 Transfer PWE (word) Transfers a parameter value (PW E ) as wor d ( 16 bit)
0010 Transfer PWE (double word) Trans fers a par am eter v alue ( P WE) as double wor d ( 32 bit)
0011 Transfer PBE element 1) T ransfers an element from t he paramet er description (PBE). The part icular PB element which is t o be
transferred is located in IND. The complet e PBE is t r ansf erred if I ND = 255.
0100 Transfer PWE (array word) 1) Transfers a parameter value (PW E ) , f r om a loc ation spec ified in IND, wit hin a one- dim ens ional field (^
array)
0101 Transfer PWE (array double wor d) 1) As pr ev ious ly , only P WE in a double- wor d format
0110 Transfer the number of array elements Transfers the number of elements of a f ield
0111 Task cannot be executed (with err or num ber ) The slav e c annot exec ute t he task . Refer to t he er r or num ber for the reas on
1000 No PKW parameter change rights Param eter v alues , param eter definit ions or as s oc iated t ex ts c annot be changed and can only be r ead
from the int er face on whic h the protocol is ex ec uted.
1001 Parameter change report ( wor d) )
1010 Parameter change report ( double wor d) )
1011 Parameter change report ( ar r ay wor d) 1) ) Refer to Sec tion 4. 2.1. 2
1100 Parameter change report ( ar r ay double wor d)
1) )
1101 Reserve
1110 Reserve
1111 Transfer text 1) 2) Text is transferred
1) For t hese tasks, to make them completely clear, the value is required which is locat ed in t he IND value in t he net data block, refer to Sec tion 4. 2.2.
2) These I Ds are only valid for the USS protocol. The I Ds are not available in the cyclic response IDs of t he PROFIBUS profile /1/ .
Table 4.2: Response IDs
Relationship between the issued task an d the asso ciated response
Task ID Response I D
(positive) I f tasks cannot be executed, the task receiver
sends t he r es pons e ID " task c annot be exec uted"
and trans fers the appropr iate err or ID in t he
paramet er v alue ( P WE) :
ID Function ID Function
0000No task 0000No response Error ID Description
0001Request P WE 0001
0010Transfers PWE (word)
Trans fers P WE ( double wor d) 0 illegal PNU
0010Change PWE ( wor d) 0001Transfers PWE (word) 1 Parameter cannot be changed
0011Change PWE ( double wor d) 0010Transfers PWE (double wor d) 2 Lower or upper v alue lim it
violated
0100Request PBE element 0011Transfers PBE element
0101Change PBE element 0011Transfers PBE element 3 erroneous IND
0110Request P WE ( ar r ay ) 0100Transfers PWE (array word) 4 No array
0101Transfers PWE (array double
word) 5 incor r ec t dat a type
0111Change PWE ( ar r ay wor d) 0100Transfers PWE (array word) 6 Setting not per m itted
1000Change PWE ( ar r ay double wor d) 0101Transfers PWE (array double
word) 7 Desc r iptive elem ent not be
changed
1001Request num ber of arr ay
elements 0110Transfers the number of array
elements ::
1011Change PWE ( ar r ay double wor d)
and store in t he EEPROM 0101Transfers PWE (array double
word) 100 Reserved
1100Change PWE ( ar r ay wor d) and
store in the EEPROM 0100Transfers PWE (array word) > 100 Error IDs greater than 100 can
be assigned f or a s pec ific
converter.
1101Change PWE ( double wor d) and
store in the EEPROM 0010Transfers PWE (double word) Error I Ds 0 t o 100 are t he same as the error IDs
of the PROFIBUS profile " v ar iable- s peed dr iv es "
/1/.
1110Change PWE ( wor d) and s tore in
the EEPROM 0001Transfers PWE (word) Additional def ined er r or num ber s ar e doc um ented
in /1/.
1111Request or c hange text 1111Transfers text Error IDs, stored in a unit, can be taken from t he
Instruc tion Manual
1010Reserve 0111Task cannot be executed
Table 4.3: Task ID and associated response IDs
C: Defining the net data
Specification USS protocol C - 15
E20125-D0001-S302-A1-7600
Task / res pons e pr oc es s ing
The t as k / res pons e pr oc es s ing defines the t im ing and functional sequenc e of dat a transfer for the PK W
interface between t he m as ter and the slav es .
• A task or a r es pons e for the PK W int er face c ons is ts of inf or m ation for the t as k ID, the param eter
number, par am eter index and the param eter v alue. I f individual inform ation is not r equir ed, t hen these
are preset wit h 0.
• One task or one response always only r efers to one parameter value ( ex c eption: Index v alue 255) .
• The mas ter c an only is s ue on e t ask t o an in t erf ace and it mus t wait for the appropr iate res pons e ID.
The mas ter m us t repeat it s task as long as it wait s for the respons e ID!
• The t as k m us t be com pletely trans m itt ed in one telegram ; split task telegram s ar e not perm itt ed. T he
same is true for the res pons e!
• E ac h task c hange s ignifies a new task , which m us t have an as s oc iated res pons e. The t as k ID "no
task " should be handled the same as for any other task ID and mus t be res ponded to wit h the
response ID " no r es pons e" !
• If information is not required f rom the PKW int erface in t he cyclic mode (only PZ D data are import ant ),
then t he "no t as k " task m us t be issued.
• If there are considerable periods of time between the cyclic t elegram sequence and t he response in
the driv e c onv er ter, t he r es pons e to "old task " is trans m itt ed in the t r ans ition phase between "old task "
and "new t as k " until t he " new task " is identif ied and the ass oc iated res pons e c an be is s ued.
For r es pons es whic h c ontain param eter v alues , t he s lav e alway s r es ponds with the actual value
when the res pons e telegram is r epeated.
• When com m unic ations ar e firs t established between t he m as ter and s lav e ( the fir s t t im e that the slav e
responds) , t he s lav e c an, in t he trans ition phase in whic h a r es pons e is being pr epar ed in the
converter, only r es pond with t he ID "no r es pons e" .
• If the mas ter does not rec eiv e a r es pons e ID t o his task from the addres s ed s lav e, t hen the mas ter
must r es pond appr opr iately.
• If the master does not have t he paramet er change rights, all change and EEPRO M tasks fr om the
drive conv er ter ar e not proc es s ed, and are r es ponded to wit h the I D " no par am eter c hange r ights" . All
read tasks are processed.
• The slav e does not expec t an ack nowledgem ent fr om the mas ter that the res pons e has been
received.
• Ident ification of the res pons e to a t as k is s ued by the mas ter:
The mas ter c an identif y the cor r ec t res pons e in the res pons e telegram by ev aluating the r es pons e ID
(Table 4.2), t he par am eter num ber ( P NU) and if requir ed, t he v alue in IND.
• Ident ifying a new task in the slav e:
Every task , which is gener ated by the mas ter aft er a v alid r es pons e for t he old task has been
received, is identif ied as a new task .
• The mas ter trans m its a br oadc as t t elegr am ,
it is not perm is s ible that the slav es s end a r es pons e telegram to t he m as ter as r es ult of this br oadc as t
telegram.
C: Defining the net data
C - 16 Specification USS protocol
E20125-D0001-S302-A1-7600
4.2. 1.2. Parameter ch ang e repo rt
Bit No. 11 is defined as toggle bit in t he PKE f or processing parameter change reports . A slave sends a
paramet er c hange r epor t t o the mas ter when a par am eter v alue ( P WE) is c hanged, if this c hange is not realized
via the interface whic h is us ed for c om m unic ations between t he m as ter and s lav e.
All parameters are def ined (PBE) as eit her active or passive parameter using a bit, so that a parameter change
report is not sent at each parameter value change. This bit is included in the descript ion in t he "ID" element
(ref er to F ig. 6. 1) . A par am eter c hange r epor t is only s ent when t he P WE c hanges for active par am eters !
The f ollowing pr oc es s ing m ec hanis m is ex ec uted f or a par am eter c hange r epor t:
The st andard task / response sequence, as described in Section 4.2. 1. 1, is immediat ely interrupted by the slave
by tr ans m itt ing, in t he r es pons e telegram , t he r es pons e ID "par am eter c hange r epor t" ( IDs 9,10, 11 and 12 from
Table 4. 2) with t he appr opr iate parameter num ber ( P NU) and the changed par am eter v alue ( P WE) .
Simult aneous ly , t he s lav e c hanges the param eter c hange r epor t t oggle bit (No. 11), and in so doing, the slav e
indicates that the available par am eter c hange r epor t is new for the mas ter. The param eter c hange r epor t is
trans m itt ed to t he m as ter until t he m as ter ac k nowledges that the parameter c hange r epor t has been definit ely
received by c hanging the t oggle bit (bit 11). Aft er this, the s lav e c ontinuous with t he interrupted response
processing, or it t r ans m its t he nex t available par am eter c hange r epor t. This m eans , t hat if s ev er al par am eter
change reports ar e av ailable, t he nex t param eter c hange r epor t can only be s ent af ter t he pr ev ious par am eter
change report has been ac k nowledged.
Changing all parameter val ues i n an array:
If all v alues of a param eter ar r ay ar e c hanged us ing a telegram v ia an interface ( index low by te = 255) , and if
only fixed t elegram lengt hs are possible at a second int erface, only the appropriate response ID (AK 9 to 12),
the param eter num ber and the index low by te = 255 ar e trans ferr ed as par am eter c hange r epor t via this
interface. I n this c as e, t he c hanged par am eter v alues ar e not trans ferr ed.
C: Defining the net data
Specification USS protocol C - 17
E20125-D0001-S302-A1-7600
Example:
Data t r ansf er between t he mast er and slave when two paramet er change report s are present (SPM 1, SPM 2);
bit 11 of the param eter ID is obs er v ed ( in br ac k ets) :
Master Bit 11 in PKE Slave
SPM 1 present, bit No. 11 in the
response telegram is set from
0 to 1 (toggled)
Identifies a change in bit 11
from the previous task telegram
-> SPM 2 can only be sent.
Bit 11, from 1 to 0 in the
response telegram
Identifies a change in bit 11
from the previous task ->
response to task 2 is sent.
Identifies SPM 1, and sets
bit 11 in the task telegram
from 0 to 1
Is not received
Identifies SPM 2, and sets
Bit 11 in the task telegram
from 1 to 0
Task 1 (0)
Response 1(0)
Task 2 (0)
(1) SPM 1
(Task 2) (1)
SPM 1 acknowledged
SPM 2(0)
Task 2 (1)
SPM 2(0)
(Task 2) (0)
SPM 2 acknowledged
(0) Response 2
Fig. 4.5: Data sequence for parameter change reports
C: Defining the net data
C - 18 Specification USS protocol
E20125-D0001-S302-A1-7600
4.2. 1.3 Parameter number ( P NU)
The paramet er number (PNU) is contained in bits 0 to 10 in the parameter I D (PKE). The assignment of a
function / s ignificanc e to a PNU ( e. g. the int egr al- ac tion t im e TN for the arm ature c ur r ent is s tored under
paramet er num ber P 156 for 6RA 24 S IMOREG K) , is dependent on t he dr iv e c onv er ters and m us t be t ak en from
the relev ant I ns truc tion Manual.
4.2. 2. In dex (IND)
PKE IND PWE
No: 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Low byte: 0 to 255
High byte bits 10 to 15:
Drive converter-specific
High byte bit 8 and bit 9: Read
and write text extension
xxxxxxxx
xxxxxxxx
Fig. 4.6: Index structure
Using the IND f or the t as k / res pons e ID f r om S ec tion 4. 2.1. 1.
The index is used f or t he following t asks:
•Reading and writing t he parameter descript ion
•Reading and writing v alues whic h ar e loc ated in an arr ay ( = one-dim ens ional field)
•Reading and writing texts
In all ot her c as es , bit s 0 to 9 are s et t o logic al 0.
The driv e c onv er ter- s pec ific bits 10 to 15 may only be ev aluated by dr iv e c onv er ters , which are defined f or
these bits. F or dr iv e c onv er ters , where no function is s tored under bits 10 to 15, then t he bits ar e s et t o logic al
0. T he mast er must take this into account when issuing tasks t o the appropriate slaves.
C: Defining the net data
Specification USS protocol C - 19
E20125-D0001-S302-A1-7600
Task I D ( mast er → slave):
•Reading and writing t he parameter descript ion
•Reading and writing v alues from an ar r ay
Index low byte: 0 - 254
PKE IND
Task I D bi t :
15 14 13 12 Function Low byte Function
0 1 0 0 Request PBE element y (< 254) Read the yth element
0 1 0 1 Change PBE element y (< 254) Change the yt h elem ent
0 1 1 0 Request P WE ( ar r ay ) y (< 254) Read the par am eter value
from the yth position in t he
array
0 1 1 1 Change PW E ( ar r ay wor d) y (< 254) W r ite t he P WE in s ingle wor d
form at t o the yth position in
the arr ay
1 0 0 0 Change PW E ( ar r ay double
word) y (< 254) W r ite t he P WE in double- wor d
form at t o the yth position in
the arr ay
1 1 0 0 Change PW E ( ar r ay wor d) and
store in the EEPROM y ( < 254) Wr ite t he P WE ( wor d) to t he
yth pos ition in t he ar r ay in the
EEPROM
1 0 1 1 Change PW E ( ar r ay double
word) and store in t he EEPRO M y (< 254) W r ite t he P WE ( double wor d)
to t he y th position in t he ar r ay
in the EEPRO M
Table 4.4: Task ID and index for indexed parameters
Index low byte: 255
The index low by te = 255 has a spec ial s ignificanc e. F or this index v alue, t he task is r eferr ed to the c om plete
array or the complet e paramet er description.
Error-free processing of such a t ask assumes that the system has been parameterized for a variable t elegram
length (PKW _ANZ = 127).
If t he length (in words) of a paramet er description or an array exceeds t he maximum possible lengt h of the
PKW area, r efer to Sec tion 4. 1.2, then t he task s hould be r es ponded to with r es pons e ID 7 (task c annot be
execut ed) , and an err or m es s age ( = err or num ber ) .
The proc edur e is the sam e, if the low byte = 255, param eteriz ed for fixed telegram length.
C: Defining the net data
C - 20 Specification USS protocol
E20125-D0001-S302-A1-7600
Task I D ( mast er → slave)
•Reading and writing a text (^ t ex t element )
Only v alid for S IMOVE RT Mas ter Dr iv es
Texts ar e s truc tured in the driv e c onv er ter ac c or ding to t he P ROFIBUS-profile definitions " v ar iable- s peed
drives" / 1/. Further, f or S IMOVE RT Mas ter Driv es , an extension ov er /1/ is defined, whic h allows , f or an index ed
paramet er ( = ar r ay ) , both a text f ield with t ex t elements for eac h index , as well as a text f ield with t ex t elements,
for each paramet er value, can be stored. According to /1/ , it is only possible t hat only one t ext field can exist f or
a paramet er . I n or der to be able t o r ead or wr ite t hes e text elements, or t o be able to selec t which of t he two
text f ields is to be addres s ed, t he high by te in t he index ( IND) is us ed.
Error-free processing wit h t ask ID always requires parameterizat ion for a variable telegram length (PKW_ANZ =
127). If a fixed telegram length is par am eteriz ed for this t as k , t hen it mus t be also r es ponded to wit h r es pons e
ID 7 and err or num ber .
Index low byte: 1 - 254 and index high byte, bits 8 and 9
PKE IND
Task I D
bit:
15 14 13 12
Function Index
high byte
Bit No. :
9 8
Index
low byte Note
1 1 1 1 Reads t he y th t ex t element in a
text f ield whic h ex is ts for
paramet er s , dat a type:
- Array
- Uns igned 8/16/ 32
-V2
0 0 1 < y < 254 The yt h text element is
described in /1/
Sect ion 5.1. 2.4.
1 1 1 1 Wr ites the yth t ex t element in the
text f ield whic h ex is ts for data
types:
- Array
- Uns igned 8/16/ 32
-V2
0 1 1 < y < 254 " as abov e"
Table 4.5: Task ID and index when reading and writing texts
Content s of t he text elements for par am eters , data type:
•Array: T ext , which describes the significance of the individual array indices.
•Unsigned 8/16/ 32: Text , which describes the significance of t he individual paramet er values of t his
parameter.
•V2: T ext , which describes t he significance of the bit values " 0" and " 1" of every bit in the V2 paramet er.
Index low byte: 255
The spec ial s ett ing, low byte = 255, has no s ignificanc e! A task s o is s ued m us t be res ponded to with r es pons e
ID 7 and err or num ber .
C: Defining the net data
Specification USS protocol C - 21
E20125-D0001-S302-A1-7600
A "s ec ond" additional t ex t f ield is defined for par am eters , dat a type ar r ay , in which text elements are s tored,
which describe the signif icance of the individual parameter values.
PKE IND
Task I D bi t :
15 14 13 12 Function Index
high byte
Bit No. :
9 8
Index
low byte Note
1 1 1 1 Reads t he y th t ex t element fr om
the " s ec ond" text f ield to a
paramet er , dat a type ar r ay .
1 0 1 < y < 254 y = parameter v alue+1
1 1 1 1 Wr ites the yth t ex t element from
the " s ec ond" text f ield to a
paramet er , dat a type ar r ay .
1 1 1 < y < 254 y = parameter v alue+1
Table 4.6: Task ID and index when reading and writing the text elements of an array
Task I D ( mast er → slave)
Index high byte, bits 10-15:
These bit s can be used converter-specific, and must be described in the associat ed I nstruct ion Manual of the
drive conv er ter. "0" should be sent as default v alue for dr iv e c onv er ters , which do not use these bit s .
Convert er family Signific anc e of bit s 0- 15
SIMOVERT P 6SE21
Micro Master
SIMOVERT P 6SE12 /6SE35 with
communic ations boar d C51/61
SIMOVERT K 6RA24
SIM OREG K 6RA 23
SIMOVERT Master Drives
SIMOVERT PM
SIMOVERT P 6SE48
None
None
None
None
None
None
Address ing the inf eed unit and t he inv er ter
Charact er is tic num ber
Table 4.7: Significance of the converter-specific bits 10 to 15 in the index
C: Defining the net data
C - 22 Specification USS protocol
E20125-D0001-S302-A1-7600
Respo nse I D ( slave → master):
PKE IND
Respo nse I D
bit:
15 14 13 12
Function Index
low byte Function
0 0 1 1 Transfer PBE element y (≤ 254) Trans fer y th element
255 Trans fer c om plete PB E
0 1 0 0 Transfer PWE (array word) y (≤ 254 Trans fer the PWE, which is
located at t he y th position in
the arr ay ( wor d form at)
255 Trans fer the com plete arr ay
(word f or m at)
0 1 0 1 Tr ans fer P WE ( ar r ay double
word) y (≤ 254) As abov e, only PWE as
double word
255 Trans fer c om plete arr ay
(double word f or m at)
1 0 1 1 Param eter c hange r epor t (ar r ay
word) y (≤ 254) Tr ans fer a changed P WE as
word for m at wit h a par am eter
change report, wher eby P WE
is locat ed at t he y th position in
an array
255 Trans fer c om plete arr ay , if
variable t elegr am length is
activ e with t his interface
1 1 0 0 Param eter c hange r epor t (ar r ay
double word) y (≤ 254) As above, only PWE as
double word for m at
255 Trans fer c om plete arr ay , if
variable t elegr am length is
activ e at t his interface
Table 4.8: Response ID and index for indexed parameters
Tran sf er respo nse I D f or text elemen t , SIMOVERT Mast er Drives:
PKE IND
Respo nse I D
bit:
15 14 13 12
Function Index
high byte
Bit No. :
9 8
Index
low byte Function
1 1 1 1 Trans fer text element x x 1 < y < 254 Transfer text elements
according to t he
partic ular task
Table 4.9: Response ID and index when reading and writing texts
Note: x : 0 or 1, depending on t he par ticular task .
C: Defining the net data
Specification USS protocol C - 23
E20125-D0001-S302-A1-7600
4.2. 3. Parameter val ue (P WE)
PKE IND PWE 1
Bit-Nr.: 15 14 13 12 11 10 9 8 7654321
0
PWE 2
High-Byte Low-Byte
Fig. 4.7: Structure, parameter value
The ass ignm ent of P WE is dependent on t he par ticular task , res pec tive of the as s oc iated res pons e.
Task teleg ram ( mast er → sl ave)
PKE PWE Length of the PKW range in
the net data block
Task I D
bit:
15 14 13 12
Function Contents Fixed
(min.)
Variable
necessary
0 0 0 0 No t as k x ^ not as s igned 3 words
0 0 0 1 Request PWE x 3 words
0 0 1 0 Change PWE ( wor ds ) Value 3 words -
0 0 1 1 Change PWE ( double wor d) PWE 1 = high word
PW E 2 = low word 4 words
0 1 0 0 Request PBE element x 3 words / 4words Yes, if
0 1 0 1 Change PBE element PBE element 3 words / 4 words index low
byte = 255
0 1 1 0 Request PWE ( ar r ay ) x 3 words Yes, if
0 1 1 1 Change PWE ( ar r ay wor d) Value 3 words index low
byte = 255
1 0 0 0 Change PWE ( ar r ay double
word) PWE 1 = high word
PW E 2 = low word 4 wor ds Yes, if
index low
byte = 255
1 0 0 1 Request number of arr ay
elements x 3 words -
1 1 0 0 Store c hanged v alue ( ar r ay
word) in the EEPROM Value 3 words Yes , if
index low
byte = 255
1 1 0 1 Store c hanged v alue ( double
word) in the EEPROM PWE 1 = high word
PW E 2 = low word 4 wor ds
1 1 1 0 Store c hanged v alue ( wor d) in
the EEPROM Value 3 words -
1 1 1 1 Request or c hange text - X = for " r eques t"
- tex t element:
for "change"
No Yes
Table 4.10: Parameter block length in the task telegram
C: Defining the net data
C - 24 Specification USS protocol
E20125-D0001-S302-A1-7600
Respo nse teleg ram ( slave → master)
PKE PWE Length of the PKW range in
the net data block
Respo nse I D
bit:
15 14 13 12
Function Contents Fixed
(min.)
Variable
required
0 0 0 0 No res pons e x ^ not ass igned 3 words -
0 0 0 1 T r ans fer P WE ( wor d) Value 3 words -
0 0 1 0 T r ans fer P WE ( double wor d) PWE 1 = high word
PW E 2 = low word 4 words -
0 0 1 1 Transfer PBE element
IND < 254 Element 3 words /
4 words -
IND = 255 All elem ents No Yes
0 1 0 0 Transfer PWE (array word)
IND = y Value ( wor d) from
the yth position in t he
array 3 words Yes, if
index low
byte = 255
0 1 0 1 T r ans fer P WE ( ar r ay double
word)
IND = y
Value (double word)
from the yth position
in the arr ay 4 words Yes, if
index low
byte = 255
0 1 1 0 T r ans fer the number of array
elements Num ber of arr ay
elements 3 wor ds -
0 1 1 1 Task cannot be executed Error number 3 words -
1 0 0 0 No PK W change r ights x 3 words -
1 0 0 1 Par am eter c hange r epor t
(word) Value ( wor d) 3 words -
1 0 1 0 Par am eter c hange r epor t
(double word) Value (double word) 4 words -
1 0 1 1 Par am eter c hange r epor t
(array word)
IND = y
Value (word) from
the yth position in t he
array
3 words -
1 1 0 0 Par am eter c hange r epor t
(array double wor d)
IND = y
Value (double word)
from the yth position
in the arr ay
4 words -
1 1 1 1 T r ans fer text T ex t elements No Y es
Table 4.11: Length of the parameter block in the response telegram
Note:
If P K W_ANZ is s et t o 4, word form ats ar e s ent in t he low wor d ( P WE2) . In this c as e, t he high wor d ( P WE1) is
0.
If P K W_ANZ is s et t o 127 ( v ar iable length), word form ats ar e s ent in PWE1, double- wor d form ats in P WE1
(high word) and P WE2 ( low wor d) .
C: Defining the net data
Specification USS protocol C - 25
E20125-D0001-S302-A1-7600
5. PZD area
The proc es s data (P ZD) ar ea is independent of the PK W area of t he s ec ond s ec tion in t he net data bloc k .
5.1. Structu re of t he PZD area
The PZD-ar ea s truc ture is alway s the sam e as far as the sequenc e of its elem ents (^ words ) , and only diff er s
from the standard s truc ture by the number of t r ans ferred s etpoint s / actual values .
Stan dard st ructure:
PZD1 PZD2 PZD3
1 word 1 word 1 word
PZD16
1 word
Max. 16 words
Min. 0 words, i. e. no PZD area in the net data block
Fig. 5.1: Structure of the process data area PZD
PZD1 PZD2 PZD3 ... PZD16
Task telegram
(master → slave) Control word Main setpoint Setpoints /
supplement ar y c ontrol
words
Response t elegr am
(slave → master) Status wor d Main act ual v alue 1) A c tual values 1) /
supplement ar y s tat us
words
Table 5.1: Structure of the process data area PZD
Note:
The rec eiv ed P ZD mus t always be pr oc es s ed with high prior ity in the mas ter and s lav e. PZ D pr oc es s ing has
priorit y ov er P K W proc es s ing, and always trans fers the mos t cur r ent dat a av ailable at the interface.
1) T he s etpoint - ac tual value as s ignm ent can be s elec ted as r equir ed, i. e. f or ex am ple, the s peed s etpoint is
trans ferr ed in the t as k telegram in P ZD2, then t he s peed ac tual value c an be s ignaled bac k in the
response telegram in P ZD2 (this m ak es s ens e from a technologic al per s pec tive) , or also a diff er ent
actual v alue s uc h as torque ac tual value, position actual value or c ur r ent actual value.
C: Defining the net data
C - 26 Specification USS protocol
E20125-D0001-S302-A1-7600
5.2. Description of the individual PZD elements
5.2.1. The control word and status word
The control and s tat us wor ds ar e identical with t he definit ion from the PROFIBUS "drive technology" profile / 1/.
No.: 15 14 13 12 11 10 9 8 7 6 5 4 3 2 10
Refer to tables
status word
Control actual value
Main setpoint-
Fig. 5.2: Structure of the control- and status word
The cont rol and status words, which are specif ied by a high-level aut omation syst em via t he " USS bus"
corres pond ex ac tly, f or bits 0 to 10, to t he definit ions whic h ar e s pec ified for trans m is s ion v ia the PROFIBUS, in
the "v ariable-speed drives" profile /2/. The ot her remaining bit s are assigned, convert er-specif ic.
C: Defining the net data
Specification USS protocol C - 27
E20125-D0001-S302-A1-7600
Control word (bits 0 to bit 2)
Bit Value Significance Comments
0 1 ON Ready; v oltage available at t he c onv er ter, i. e. main c ontactor in (if
available); the f ield is es tablished; if pr ogr es s ion is not realiz ed
within a delay time, which c an be par am eteriz ed ( t delay), t hen the
"switch- on inhibit" s tatus is entered.
tdelay = 0 ... 20 min, 20 min is interpretted as being infinit e
Converter-specific:
Version 1: Field is es tablished ( s tandstill f ield) ;
pulses are inhibited
Version 2: DC link is char ged; inver ter puls es ar e inhibited.
Version 3: Rectifier and inv er ter puls es ar e inhibited,
commutat ing c apac itors ar e not char ged, nor
post-charged
Version 4: Field-, rec tif ier - and inv er ter puls es ar e inhibited.
0 OFF 1 Shutdown (depending on the stat us of control word bits 0,1 and 2
retur n to t he s tat us " s witch- on inhibit", "not ready to switch- on" or
"ready to switch-on"); dec eler ation along t he r am p- function
generator r am p, or at t he DC link v oltage limit;
at n/ f = 0 and I = 0, supply is dis c onnec ted: M ain c ontactor out (if
available)
1 1 Operating condition All "OFF 2" commands ar e c anc eled.
0 OFF 2 Voltage dis c onnec ted:
Converter-specific:
Version 1: Shift pulses to t he firing angle lim it αmax; inhibit
pulses at I =0.
Version 2: Inhibit puls es .
Version 3: Shift pulses to t he firing angle lim it αmax; inhibit
the rec tif ier and inv er ter puls es at I = 0.
Version 4: As ver s ion 3, addit ionally ex c itat ion and exc itat ion
contactor out.
The main c ontactor is then switched- out (if available) and the drive
goes into the switch- on inhibit condition; the motor c oas ts down.
2 1 O per ating condition All "OFF3" commands are canc eled.
0 OFF 3 Fast stop, if necessary cancel operating inhibit , f as t as poss ible
decelerat ion, e. g. along t he c ur r ent limit or at t he DC link lim it at
n/f = 0; inhibit r ec tif ier puls es , t hen the power is dis c onec ted
(cont ac tor out) and the driv e goes into t he s witch- on inhibit
condition.
Table 5.2: Assignment of control word bits 0 to 2
C: Defining the net data
C - 28 Specification USS protocol
E20125-D0001-S302-A1-7600
Control word (bit 3 to bit 7)
Bit Value Significance Comments
3 1 Enable oper ation Enable elect r onic s + puls es
Converter-specific:
Version 1: Enable excitat ion.
Version 2: If c onfigured, de-ener giz ation t im e delay then t he
invert er puls es ar e enabled and the exc itat ion
current impr es s ed
Version 3: If c onfigured, de-ener giz ation t im e delay , t hen the r
rect ifier and inv er ter puls es ar e enabled.
Commut ating capac itors pr e- c har ge.
Version 4: Pulses enabled for r otor pos itioning, then t he
rect ifier and c onv er ter puls es ar e enabled.
The driv e then acc eler ates to t he s etpoint .
0 I nhibit operation Converter-specific:
Version 1: Shift pulses to t he firing angle lim it αmax; inhibit
pulses at I = O, and set exc itat ion to t he s tandstill
excit ation level.
Version 2: Inhibit inv er ter puls es .
Version 3: Shift rec tif ier puls es to t he firing angle lim it αmax;
inhibit rec tif ier and inv er ter puls es at I = 0.
Version 4: Shift t he r ec tif ier puls es to t he firing angle lim it α
max; inhibit r ec tif ier , inver ter and ex c itat ion puls es
at I = 0.
The driv e c oas ts down ( r am p- function generator to 0, or trac k ing)
and the driv e goes into t he "ready" st atus ( r efer to t he c ontrol wor d,
bit 0).
4 1 O per ating condition
0 I nhibit ram p- function
generator Ram p- function generator output is s et t o 0. T he m ain c ontact or
remains in, t he c onv er ter is not isolated f r om the supply , driv e
decelerat es along the cur r ent limit or at t he DC link lim it.
5 1 Enable r am p-
function generator
0 Hold ram p- function
generator The setpoint from the ram p- function generator is held.
6 1 Enable s etpoint S elec ted value at the input of the ram p- function generator is
switched-in.
0 I nhibit setpoint Selected value at t he input of the ram p- funct ion gener ator is s et t o
0.
7 1 Ac k nowledge Group signal is ac k nowledged at t he r is ing edge; conv er ter is in the
"f ault" c ondition unt il the fault is r em ov ed, and t hen goes into t he
"switch- on inhibit" c ondition.
0 No significanc e
Table 5.3: Assignment of control word bits 3 to 7
C: Defining the net data
Specification USS protocol C - 29
E20125-D0001-S302-A1-7600
Control word (bit 8 to bit 15)
Bit Value Significance Comments
8 1) 1 Inching 1
ON Prerequis ite: Operation is enabled and n ( s et) = 0.
Drive acc eler ates as fast as pos s ible to inching s etpoint 1
0 I nc hing 1
OFF Drive brak es as fast as pos s ible, if " inc hing 1" was pr ev ious ly ON,
and goes into the condition "oper ation enabled" at n/ f = 0 and I = 0"
9 1) 1 I nc hing 2
ON Prerequis ite: Operation is enabled and n ( s et) = 0.
Drive acc eler ates as fast as pos s ible to inching s etpoint 2
0 I nc hing 2
OFF Drive brak es as fast as pos s ible, if " inc hing 2" was pr ev ious ly ON,
and goes into "operation enabled" at n/f = 0 and I = 0
10 1 Control from the
PLC Control via interface, proc es s data valid
0 No control Proces s data invalid, i. e. t he " old" pr oc es s data are r etained
11-15 Convert er-specific Signif icance not specified
Table 5.4: Assignment of control word bits 8 to 15
1) The ass ignm ent of the inching function t o bits 8 and 9 is optional.
Explanations:
AG PLC SM Synchr onous m otor
ASM Induct ion m otor SPM Param eter change r epor t
ER Excitat ion UZK DC link
GR Rectifier WR Inverter
HLG Ramp-func tion generator
αmax Max. firing angle
Version 1: DC c onv er ter
Version 2: P WN voltage-sour c e DC link c onv er ter
Version 3: Cur r ent-sour c e DC link c onv er ter with induction motor
Version 4: Cur r ent-sour c e DC link c onv er ter with sy nc hr onous m otor ( c onv er ter- fed motor)
C: Defining the net data
C - 30 Specification USS protocol
E20125-D0001-S302-A1-7600
Status word (bit 0 to bit 7)
Bit Value Significance Comments
0 1 Ready to switch- on Power supply s witched- on,
electr onic s initialized,
main cont ac tor, if av ailable, dropped- out,
pulses inhibit ed
0 Not r eady to switch-
on
1 1 Ready Refer to control word, bit 0
0 Not r eady
2 1 O per ation enabled Ref er to control wor d, bit 3
0 O per ation inhibit ed
3 1 F ault Drive fault ed and thus non- oper ational, goes into t he s witch- on
inhibit stat us aft er ac k nowledgem ent if the f ault has been r em ov ed.
Fault num ber s ar e loc ated in t he fault par am eters
0 Fault-free
4 1 No OFF 2
0 OFF 2 "OFF 2" command available
5 1 No OFF 3
0 OFF 3 "OFF 3" command available
6 1 Switch- on inhibit Re-closur e only us ing " OFF 1" and then " ON"
0 No switch- on inhibit
7 1 Alar m Drive operational again; alar m in the maint enanc e- s er v ic e
paramet er ; no ack nowledgem ent
0 No alarm No alarm pres ent or alar m has dis appear ed.
Table 5.5: Assignment of the status word bits 0 to 7
C: Defining the net data
Specification USS protocol C - 31
E20125-D0001-S302-A1-7600
Status word (bit 8 to bit 15)
Bit Value Significance Comments
8 1 Setpoint-actual
value monit or ing in
the t oler anc e r ange
Act ual v alue within a t oler anc e bandwidth; dy nam ic v iolations
permiss ible for t < tmax, e. g.
n = nset ± n,
f = fset ± f, etc.
tmax can be paramet er iz ed
0 Not in the t oler anc e
range
9 1 Cont rol request ed The aut omation system is requested t o t ake control.
0 Local oper ation Control is only pos s ible at t he c onv er ter
10 1 f or n r eached Actual value > com par is on v alue (set point), which c an be s et via
the param eter num ber
0 f /n f allen below Actual v alue < com par is on v alue
11-15 Convert er-specific Signif icance is not specified
Table 5.6: Assignment of status word bits 8 to 15
C: Defining the net data
C - 32 Specification USS protocol
E20125-D0001-S302-A1-7600
5.2.2. Setpoints / actual values
15 14 13 12 11 10 9 8 7 6 5 4 3 2 10
status word
Control- main actual value
Main setpoint
Bit No.:
Fig. 5.3: Structure of the main setpoint and main actual value
Trans fer of norm aliz ed s etpoint s and ac tual values . T he nor m aliz ation is dependent on the s ignificanc e of t he
value and the par ticular c onv er ter type.
Bit No.: 15 8 0
status word
Control main actual value
Main setpoint-
7
Fig. 5.4: Assignment of additional setpoints and actual values as well as, if necessary, additional control- and status words.
5.2. 3. Broad cast mechan ism
For S IMOVE RT Mas ter Dr iv es , a mec hanis m has been defined f or transferr ing pr oc es s data, whic h allows the
master t o simult aneously transf er cont rol word (s) and setpoints for all drives connected at the bus, in a
telegram . Using m as k ing, it is pos s ible to def ine whic h s etpoint s and whic h c ontrol wor d bits s hould ac tually be
influenced by the broadc as t t elegr am . T he m as k ing is alway s s ent in t he par ticular br oadc as t t elegr am . In this
case, a fixed length of 4 wor ds is alway s us ed in the PK W area. T his m eans , t hat "s tandard" P K W proc es s ing is
not possible f or t he broadcast t elegram. A detailed description of the broadcast mechanism is included in the
Appendix.
C: Defining the net data
Specification USS protocol C - 33
E20125-D0001-S302-A1-7600
6. Data transfer format for the net data
For net dat a, which c ons is t of m or e than one byte, for data tr ans fer v ia the bus, t he m os t significant part is f ir s t
trans ferr ed. T his definit ion is identical with t hat f or the tr ans fer of net data via P ROFIBUS. The following are
valid:
Trans fer of word form ats:
The high byte is alway s trans ferr ed before the low byte
This is v alid for all 16- bit dat a types : e. g. V2, unsigned 16, integer 16, et c . (r efer to / 1/)
Trans fer of double-wor d form ats:
A high word is alway s trans ferr ed before a low wor d. W hen trans ferr ing high and low wor ds , t he following data
trans fer r egulations apply for wor d form ats.
This is v alid for all 32- bit dat a types : e. g. unsigned 32, int eger 32, floating point , et c . (r efer to / 1/)
Transfer of byte formats:
In t his c as e, t her e is no par ticular s equenc e. Dat a is trans ferr ed in the sam e s equenc e that it is s tored in the
converter "inter nal m em or y ".
This is v alid for data, type: By te string ( = octet s tring, ac c or ding to / 1/)
Transfer of texts:
Texts ar e c om pr is ed of individual c har ac ters . Eac h c har ac ter has a by te f or m at. There is no par ticular s equenc e
for trans ferr ing the individual c har ac ters . T he c har ac ters ar e transferr ed in the sequenc e in whic h they ar e
stor ed in the conv er ter " internal m em or y " .
The dat a type for text char ac ters is the vis ible s tring, r efer to / 1/.
The dat a transf er syntax is explained in the following example using the parameter descript ion.
According to PROFIBUS profile /1/, a paramet er description belongs t o each convert er parameter. The
paramet er des c r iption it s elf cons is ts of sev er al elem ents, e. g. the ID, nor m aliz ation et c .. Depending on the
converter degree of expansion, the paramet er description is either completely or only partially present.
Struct ure, scope and significance of t he paramet er description are explained in det ail in / 1/.
C: Defining the net data
C - 34 Specification USS protocol
E20125-D0001-S302-A1-7600
The complet e parameter description of a paramet er is illust r ated in Fig. 6. 1, as this is stored in t he convert er
"int er nal m em or y " . T he ex am ple s elec ted here s hows how data is stored for S IMOVE RT mas ter dr iv es . Data is
stor ed in the conv er ter c onform ing to t he " intel" form at, whic h m eans , t hat f or ex am ple, a word, data t y pe
"unsigned 16" that the least signif ic ant byte is s tored in the least significant address .
Data type
High byte Low byte
Element No.
V2
Unsigned 16
Floating Point Fraction 2 - 2 -23
Fraction 2 - 2 -15
Exponent Fraction 2 - 2 - 7
Conversion index Parameter index
Byte-String 2
Byte-String 4 PasswordAccess group
Access rights Access rights
1. Text characters 2. Text characters
15. Text characters16. Text characters
Visible-String
As for parameter value
As for parameter value
V2
1
2
3
4
1)
1) 1st text character from the left in a display
-16
-8
- 1
ID
Number of array elements
Normalization
Parameter attribut
Access rights
Text
Upper limit
ID extension
L o we r limit
5
6
7
8
10
Fig. 6.1: Complete parameter description structure in the "internal memory" for SIMOVERT master drives
The individual elements of the param eter desc r iption are highlighted in F ig. 6. 1. T he appr opr iate dat a type of
the part icular element is shown on t he left hand side. T he element number in the parameter descript ion is
shown on the r ight hand side.
The param eter des c r iption t r ans fer v ia the bus is illus trated in F ig. 6.2.
The paramet er description can be read with the t ask "r equest PBE", refer t o T able 4.1 in Section 4.2. 1.1 fr om
the mast er. In order to read the complete paramet er description, the low byte must be set to 255 in IND; refer to
Sect ion 4.2. 2. I n or der to be able t o r ead only one element of the paramet er description, the element number
must be s et in t he low by te of IND. The "ID" elem ent is num ber 1, t he elem ent "num ber of arr ay elem ent" is
reserved for number 2, ..., number 9, the element "ID extension" is num ber 10 ( als o r efer to Sec tion 8, ex am ple
4). The slav e trans fers the param eter des c r iption in t he P K W area of the net dat a telegram . I f t he P K W area
length (in wor ds ) is defined t o be les s than (r efer to Sec tion 3) the lengt h of the elem ent t o be trans ferr ed, t he
task is r es ponded to by the slav e with t he negative r es pons e ID "task c annot be exec uted" ( Table 4. 2) . Only the
paramet er des c r iption is s hown in Fig. 6.2; the ot her net dat a c om ponents ar e not illust r ated.
C: Defining the net data
Specification USS protocol C - 35
E20125-D0001-S302-A1-7600
The dat a trans fer s equenc e is s hown in Fig. 6.2 f r om top t o bott om . This m eans , t hat at firs t, the high byte of
the I D is trans ferr ed, f ollowed by the low byte et c .
High byte
Low byte
ID
High byte
Low byte
Number of
array elements
Normalization
Expon.
-7
Frac. -2 -15
Frac. -2 -23
Quantity attribute Parameter index
Conversion index
Access rights
Password
Access group
Access rights
Access rights
Name
1. Text character
2. Text character
16. Text character
Lower limit value
Upper limit value
ID extension
High byte
High byte
High byte
Low byte
Low byte
Low byte
Frac. -2
Fig. 6.2: Transfer sequence of the parameter description via the bus
C: Defining the net data
C - 36 Specification USS protocol
E20125-D0001-S302-A1-7600
7. Configuring the protocol on the bus system
As already ex plained in the int r oduc tion, it is pos s ible to configure c om m unic ations between master and s lav es
with a f ix ed or v ar iable telegram length.
Fi xed teleg ram len gth
When c onfiguring com m unic ations with t he US S protoc ol for a fixed telegram length t his m eans :
•The f ollowing is v alid for c om m unic ations between t he m as ter and a s lav e:
The t ask- and response t elegrams have the same lengt h, i. e. the same length regarding t he PKW-
and PZD ar eas .
•This lengt h must be set before t he bus syst em is first commissioned, and may not be changed during
operation.
•A fix ed telegram length means that the net data block has a fixed s iz e.
•The net data block s iz e is s et using two param eters , refer to Section 3. 1.
The siz e of t he P K W area ( in wor ds ) is s et via par am eter " P K W_ANZ", if P K W_ANZ is s et t o 3, t he
PKW area in t he net dat a bloc k alway s takes - up 3 wor ds . T he s iz e of t he P ZD area ( wor ds ) is
appropriat ely s et via par am eter P ZD_ANZ.
For ex am ple, if P ZD_ANZ = 2, t hen the PZD area takes - up 2 wor ds in the net data block.
•If the mas ter is s ues a task whic h s hould hav e a r es pons e as r es ult, whic h would ex tend beyond the
select ed s iz e of t he P K W area, t his task m us t be res ponded to wit h the res pons e ID "task c annot be
executed".
Example:F or P K W_ANZ = 3, t he task " r eques t PWE ( double wor d) " c annot be exec uted. In t his c as e,
PKW_ANZ must be set to 4.
•Before set t ing the size of the net data block, it must be defined, which tasks are to be issued by the
mast er . Bas ed on this, t he P K W area s iz e m us t be def ined. T his m eans , t hat if double- wor d
process ing is us ed, t hen before firs t com m is s ioning, t he P K W area m us t be set to 4 wor ds , even if
most ly s ingle- wor d pr oc es s ing is us ed.
C: Defining the net data
Specification USS protocol C - 37
E20125-D0001-S302-A1-7600
Variabl e t eleg ram len gth
Data t r ans fer between mas ter and s lav e with var iable telegram length means :
•Variable t elegr am length f r om the mas ter to t he s lav e ( task telegram ) and
•Variable t elegr am length f r om the slav e to t he m as ter ( r es pons e telegram ) .
The f ollowing c onditions apply :
Variable telegram lengt h = variable PKW-area length (PKW-ANZ = 127)
•The PZ D area (process data) must always be the same size for t he task- and response telegram. This
means, that the slav e ex pec ts and trans m its, independent ly of the ac tual param eteriz ation of the PK W
area, the number of proc es s data, defined in param eter P ZD_ANZ.
•For par am eteriz ation wit h v ar iable telegram length in t he s lav e, t he " length byte" LGE in the t elegr am
fram e m us t always be ev aluated. Wit h this inform ation, and with t he fixed param eteriz ation of the
process data (par am eter P ZD_ANZ), t he length of the receiv ed, var iable task telegram c an be c lear ly
defined.
•An appropriate progr am on the mas ter s ide m us t also be c onc eiv ed, so that the variable r es pons e
telegram f r om t he slave can be identif ied and evaluated error-free. Due to the select ed t asks, as well
as infor m ation regar ding the sett ings of t he par am eters of t he indiv idual s lav es , the m as ter k nows
whether the addres s ed s lav e r es ponds with a var iable telegram .
•From the configuring, it is pos s ible, t hat slav es , which ar e par am eterized with f ix ed - and s lav es with
variable t elegr am length, c an c om m unic ate wit h a m as ter v ia the sam e bus . However , t his c an r es ult
in increased s oft war e c os ts in the mas ter.
•PKW-area structure
For a v ar iable telegram length, only the dat a whic h ar e ac tually nec es s ar y for the particular task or
response, are trans ferr ed.
Example:
Mast er : T as k , request t ex t element y →
PKW area: PKE, IND, PWE 1 (minimum 3 words)
Slave: Trans fer r es pons e, t ex t element y ( 16 c har ac ters )
PKW area: PKE, IND, PWE 1, PWE 2... PWE 8
•Monitor ing the t elegr am failures
It is diff ic ult t o s et an opt im um telegram failure time in the slave when c onfiguring v ar iable telegram
length. This is ev en m or e c r itical, t he m or e v ar ied the poss ible task v er s ions from the master to t he
slaves.
Under worst case condit ions (low baud rate, high number of nodes, long variable telegrams), t he
telegram failure time m us t be inactivated in t he s lav es .
C: Defining the net data
C - 38 Specification USS protocol
E20125-D0001-S302-A1-7600
8. Examples
8.1. Fi xed teleg ram len gth
Example 1: Transferring two words of process data (cont rol wo rd / st at us w ord , setpoint / actual value)
•Parameterization
PKW_ANZ = 0
PZD_A NZ = 2
•Task for P K W int er face not poss ible
•Only P ZD area with control wor d / stat us wor d and a s etpoint / act ual v alue in the t elegr am
Task teleg ram:
STX LGE ADR Control
word Main
setpoint BCC
Telegram frame
PZD1 PZD2
Net data
Response telegram:
STX LGE ADR Status
word Main
actual value BCC
Fig. 8.1: Telegram structure to example 1
Example 2: Transferring from a paramet er ( wo rd format) and 2 wo rds o f pro cess data
•Parameterization
PKW_ANZ = 3
PZD_A NZ = 2
•Task : Read value from par am eter No. 52 (dec im al) ; value = 4000 word form at as hex adec im al
value)
•Continuous trans fer of t he c ontrol / and stat us wor d and m ain s etpoint / actual value.
Task teleg ram:
STX LGE ADR Control
word Main
setpoint BCC
PZD1 PZD2
152 0
PWEIND
PNUAK
PKE
x
x ^ unas s igned, not r elev ant!
Respo nse teleg ram:
STX LGE ADR Status
word Actual value BCC
PZD1 PZD2
152 0 4000
PWEIND
PNUAK
PKE
H
Fig. 8.2: Telegram s truc ture to exam ple 2
C: Defining the net data
Specification USS protocol C - 39
E20125-D0001-S302-A1-7600
Example 3: E rron eou s parameter read task
As f or ex am ple 2, however
•Task: Read complete parameter description to parameter P 52
Task teleg ram:
STX LGE ADR Control
word Setpoint BCC
PZD1 PZD2
452 0
PWEIND
PNUAK
PKE
255
x
Respo nse teleg ram:
STX LGE ADR Status
word Actual value BCC
PZD1 PZD2
7
52 0
PWEIND
PNUAK
PKE
255
101
Not possible with fixed telegram length
Note: This error number must be,
for example, implemented in the converter;
is not a standard error code)
Response ID:
Task cannot be executed.
Error code
E. g. converter -dependent error number:
Fig. 8.3: Telegram structure to example 3
Example 4: Reading an element from the p aramet er descri pti on
As f or ex am ple 2, however
•Task: Read " lower limit value" element (element No. 7) fr om the parameter description t o paramet er
52. Lower lim it value = 5F FF H.
Task teleg ram:
STX LGE ADR Control
word Main
setpoint BCC
PZD1 PZD2
452 0
PWEIND
PNUAK
PKE
x
7
x ^ unas s igned, not r elev ant!
Respo nse teleg ram:
STX LGE ADR Status
word Actual value BCC
PZD1 PZD2
452 0 5FFF
PWEIND
PNUAK
PKE
H
7
Fig. 8.4: Telegram structure to example 4
C: Defining the net data
C - 40 Specification USS protocol
E20125-D0001-S302-A1-7600
Example 5: Writing a double word parameter into a p aramet er f iel d
•Fixed telegram length:
PKW_ANZ = 4
PZD_A NZ = 0
•Task : W r iting a value ( double wor d) = 4000 0000 (hex ) to param eter No. 4 at the 2nd position of the
uni-dimensional field, s tored under P NU = 4 (= ar r ay ) .
•No PZD data in t he telegram
Task teleg ram:
STX LGE ADR BCC
8 4 2
PWE1IND
PNUAK
PKE
4000H0000H
PWE2
Respo nse teleg ram:
STX LGE ADR BCC
5 4 2
PWE1IND
PNUAK
PKE
4000H0000H
PWE2
Fig. 8.5: Telegram structure to example 5
Example 6: P aramet er in a single word format for 4 w ords P KW
As f or ex am ple 5, however
•Task : W r iting a value ( wor d form at) = 7000 (hex ) to param eter No. 18.
Task teleg ram:
STX LGE ADR BCC
218 0
PWE1IND
PNUAK
PKE
07000H
PWE2
Respo nse teleg ram:
STX LGE ADR BCC
118 0
PWE1IND
PNUAK
PKE
07000H
PWE2
Fig. 8.6: Telegram structure to example 6
C: Defining the net data
Specification USS protocol C - 41
E20125-D0001-S302-A1-7600
8.2. Variabl e t eleg ram len gth
Examples for SIMOVE RT Mast er Drives
Example 7: Read a text f rom a text array which belongs to parameter 7.
P 7 is " uns igned 16" data t y pe ( ^ 02) and has a v alue r ange from 1 to 10. P 7 has a text f ield, where ev er y
parameter value is assigned a "16 character" t ext element . Text field index = paramet er value +1 (syntax
according to / 1/).
•Parameterization
Slave:PKW_ANZ = 127
PZD_A NZ = 0
•Task Read tex t element to param eter v alue 2 of P7
3rd tex t element: 300 BAUD
(According to /1/ , always 16 characters)
Task teleg ram:
STX LGE ADR BCC
15 7 0
IND
PNUAK
PKE
3
x
PWE
Respo nse teleg ram:
STX LGE ADR
BCC
15 7
PNUAK
PKE
3
IND PWE1 PWE2
B
PWE3
DU
PWE4 PWE5
0A300
Fig. 8.7: Telegram structure to example 7
C: Defining the net data
C - 42 Specification USS protocol
E20125-D0001-S302-A1-7600
Example 8: Writing and reading text elements, ind exed p aramet ers ( array)
The exam ple par am eter P 9 is an "array uns igned 16" data type ( field wit h 02 types ) with indices 1, 2 and 3.
Each index has a v alue r ange between 1 and 20. The significanc e of t he par ticular v alue r ange is the sam e for
all indices.
2 text f ields ex is t f or this par am eter:
•"f ir s t“ text field cont ains the significanc e of t he indic es
•"sec ond“ text field contains the significanc e of t he par am eter v alues
The indices , which m us t be spec ified in t he task telegram , are determined diff er ently for the t wo fields:
•"f ir s t“ text fieldindex of the tex t f iled = index of the par am eter ar r ay
•"sec ond“ text field index of the t es t f ield = param eter v alue + 1
1. T ext
field 2. Text f iel d
Index Text element t o the index Index Value Text element t o p aram. val ue
1BAUDRATE FO R S S 1 21 300 BAUD
2BAUDRATE FO R S S 2 32 600 BAUD
3BAUDRATE FO R S S 3 43 1200 BAUD
.. .. ..
21 20 1.5 MBAUD
Fig. 8.8 Text fields for indexed parameters
•Parameterization
Slave: P K W_ANZ = 127
PZD_A NZ = 0
•ID, paramet er number and index are the same in t he task- and response telegram
Possible tasks: A
KPNU IND
HB IND
LB Task teleg ram
PWE1 to PWE8
Respo nse teleg ram
PWE 1 to PWE 8
Read text element f or
index 2 15 9 0 2 - BAUDRATE FO R S S 2
Wr ite tex t element f or
index 2 15 9 1 2 BAUDRAT E FÜR SS 2 (= tas k telegram )
Read text element f or
paramet er v alue 3 15 9 2 4 - 1200 B A UD
Wr ite tex t element f or
paramet er v alue 3 15 9 3 4 1200 BAUD (= task telegram )
Task- and respo nse teleg ram:
STX LGE ADR
BCC
15 9
PNUAK
PKE
IND PWE1 PWE2 PWE3 PWE4 PWE5
xxxxxxxxxx
xxxxxx
HB LB
Fig. 8.9: Telegram structure to example 8
Appendix
Specification, USS protocol Appendix - 1
E20125-D0001-S302-A1-7600
APPENDIX
Overview: Telegram structure for the USS-protokoll
STX
LGE ADR
S tart of Text (02 Hex)
Parameter ID
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
PNU = Parameter-Nr.
Parameter change report - toggle bit (for parameter-
change"
A K = T ask and response ID
(e.g. "Change/request parameter value-,
description-, text
PKE = Parameter ID
Telegramm header
High Low
IND = INDEX for parameter field
Parameter value 1
High Low
PW E 1 e.g. high word of a double w ord
parameter)
Parameter value 2
High Low
PWE 2 e.g. lo w wo rd of a double-w ord
parameter)
Paramete value n
High Low PWEn
PZD 1 (control commands, status bits)
Main setp./act. valuet
High Low
PZD 2 (e.g. speed- frequency setpoint/
actual value)
High Low
PZDn Supplementary setpoint/actual values
supplementary control/status words
BCC B lock C heck C haracter
(EXORs all bytes
Telegram footer
PZD
PKE
C-4.2.1
Described in
Section
C-4.2.1.3
C-4.2.1.2
C-4.2.1.1
C-4.2.2
C-4.2.3
C-5.2.1
C-5.2.2
Slave address 0 - 31
T e legram len g th
(w ithout S TX and LGE , but with AD R and BC C )
Net data
Control/status word
High Low
A-4.3
A-4.2
A-4.1
A-4.4
Appendix
Appendix - 2 Specification, USS protocol
E20125-D0001-S302-A1-7600
The Optional Broadcast Mechanism of the USS-Protocol
The Br oadc as t Mec hanis m is not obligat or y for the USS s lav e interface. But if a Br oadc as t Mec hanis m is
implemented for a slave com m unication interface, it m us t be realiz ed ac c ording to this s pec ification.
Whenever t he term "Broadcast Telegram" is used in t his document, it describes a telegram that has t o be
accept ed by all dr iv es c onnec ted via a B us c onfiguration; all dr iv es fet c h ex ac tly the sam e ident ic al net data
from this telegram . A B r oadc as t T elegr am has the sam e telegram length as a norm al indiv idual telegram . (A
diff er ent t y pe of Br oadc as t T elegr am is defined in t he P ROFIBUS standard: A P ROFIBUS Broadcast Telegram
is a "mult iple length" t elegram whereby the individual inf ormat ion blocks required for all drives connected to t he
bus are contained in one extra long " gr oup- telegram " .)
It is a typic al applic ation of a B r oadc as t T elegr am to enable t he r am p gener ators of all driv es at the s am e point
of t im e by m eans of only one telegram in or der to let all dr iv es r am p up s im ultaneously.
Select ive Reaction to a Broadcast T eleg ram
According to the experience with other protocols, a Broadcast Telegram from an external
communication partner only makes sense if a ' selective reaction' to a Broadcast Tel egram i s
made possible. This means that t he d rives must be told in the net data what REF VALUES and
what Command Bits should be influenced by the Broadcast T eleg ram and wh at P ROCESS
DATA (PZD) should not be affected (the latter mentioned data must be dropped and instead the
signals transmitted in the last "Non-Broadcast Telegram" remain ef f ect ive).
The f ollowing c ons truc tion is s pec ified f or this pur pos e: A B r oadc as t T elegr am is m ar k ed by a " 1" in bit 5 of the
Address-Byte in t he t elegram header. In case of a Broadcast Telegram the PARAMETER DATA area (PKW) is
"mis us ed" for trans m itting the inf or m ation of how to reac t t o the Br oadc as t Telegr am ins tead of trans m itt ing the
normal PA RA M E TER DA TA.
If t he master station issues a Broadcast Telegram it is not allowed to enter a parameter into the PARAMETER
DATA ar ea - as it does with norm al telegram s - but instead it has to ent er a 4 Words " B ROADCA S T ENAB LE
ARRAY" int o this spac e ( r efer to F ig. 2. 5.1. 6) . T his does not caus e any pr oblem s becaus e r eading and wr iting
paramet er s v ia a B r oadc as t T elegr am is nons ens e s inc e: Br oadc as t T elegr am s , as a gener al pr inc iple, are
never answer ed by the driv es .
The BRO ADCAST ENABLE ARRAY contains Enable-Bits f or each of the PROCESS DATA W ORDS 1 to 15
and for each of t he max. possible 48 Command Bit s in the Broadcast Telegram. I f a PRO CESS dat a block
originates from a B r oadc as t T elegr am , t hen a Com m and B it or a RE F VA LUE is only ac c epted by the drive if
the related Enable B its ar e s et t o 1. I f f or a Com m and B it or a RE F VALUE the related bit s in the BROADCA S T
ENABLE A RRA Y ar e r es et, the Comm and B it or RE F VA LUE r em ains in the old st ate which has been s et by
the last Non-Broadcast - Telegram. The rules for processing t he PROCESS DATA W ORDS of a Broadcast
Telegram according t o t he Bits in t he BRO A DCAST ENABLE ARRAY are described below.
Appendix
Specification, USS protocol Appendix - 3
E20125-D0001-S302-A1-7600
Rules for processing the PROCESS DATA W ORDS of a Broadcast T elegram
The 16 PRO CESS DAT A WORDS 1 to 16 can be classified into t he f ollowing 3 groups:
- PROCESS DATA WORDS 2, 3 and 6 to 15:
These PRO CESS DAT A W ORDS can contain REF VALUES only ; they cannot act as COMMAND
WO RDS. A PROCESS DATA WORD of this group is only picked up by the LOWER SI DE BOARD fr om
a Broadcas t T elegr am if t he c or r es ponding enable bit in W or d a of t he B ROADCAS T ENA B LE A RRA Y is
set to "1".
- PROCESS DATA WORDS 1, 4 and 5:
These PRO CESS DAT A W ORDS can act as COMMAND W O RDS: WORD 1 is always a CO MMAND
WORD, ac c or ding to t he P ROFIBUS-Profile (Lit. [2]) . W ords 4 and 5 may eit her be COMMAND W O RDS
or REF V A LUE S , e. g. depending on t he s oft war e type of t he TECH B OARD.
For each of t he 48 bits of these PROCESS DATA W ORDS there is a corresponding bit in t he words b, c
and d of t he B ROADCA S T ENA B LE A RRA Y .
A PROCESS DATA Bit in the PROCESS DATA WO RDS 1, 4 and 5 is only taken over fr om a Broadcast
Telegram if
I) the whole PROCESS DATA W ORD is enabled via a "1" I nformation in the
corres ponding bit in W or d a and additionally
II ) t he PROCESS DAT A Bit it self is enabled by the corresponding bit of word b, c
or d respectively.
As a general rule it is prescribed t hat in case of a Broadcast Telegram the BROADCAST ENABLE
WORDS b, c and d m us t always be pr oc es s ed by the mas ter s tat ion and the slav e s tat ion ir r es pec tive of
the f act whether the corresponding PROCESS DATA WO RDS 1 4 and 5 are REF VALUES or
COMMAND W ORDS. This rule makes t he implement ation of a general-purpose PROCESS DAT A
receive function block eas ier ( e.g. for a S IMA DY N D fashioned TECH BOARD) . As a c ons equenc e of t his
e.g. all bit s in Bit mask d have to be set by the host system even if PROCESS DATA W O RD 5 is a REF
VALUE and is to be af fected by the Br oadc as t T elegr am .
- PROCESS DATA WORD 16
The 16t h PRO CESS DATA W O RD is not supported by the Broadcast mechanism; this means: Word 16
is not B r oadc as t-c apable and nev er taken ov er from a B r oadc as t T elegram . T he m as ter s tat ion c an
modify t his word via a Non-Broadcast Telegram only.
The rules f or processing t he PROCESS DATA WORDS of a Broadcast T elegram are summarized in the
following t able:
PROCESS
DATA WORD
BROADCAST ENABLE bi t s
which must be taken int o account
WORD 1 Bit m as k a ( B it 1) and B it mas k b
WORD 2 Bit m as k a ( B it 2)
WORD 3 Bit m as k a ( B it 3)
WORD 4 Bit m as k a ( B it 4) and B it mas k c
WORD 5 Bit m as k a ( B it 5) and B it mas k d
WORDS 6 t o 15 Bit m as k a ( B its 6 t o 15)
WORD 16 not t ak en ov er from a B r oadc as t T elegr am
(not B r oadc as t-c apable)
Appendix
Appendix - 4 Specification, USS protocol
E20125-D0001-S302-A1-7600
Example 1 o f a Broad cast Tel egram:
The host system wants to give the same Main Reference Value 'REF 1. ' to all drives connect ed t o the bus via a
Broadcast T elegram. All other PROCESS DATA of the telegram should be ignored by the drives.
In t his case the host system has to transmit the following information in the BROA DCAST ENABLE ARRAY:
Word a = 0000 0000 0000 0101 (Broadcast Flag set and
PROCESS DATA WORD 2
enabled)
Words b to d = 0000 0000 0000 0000
Example 2 o f a Broad cast Tel egram:
The host syst em wants to start the ramp generators of all drives connected to the bus simultaneously via one
Broadcast T elegram. All other PROCESS DATA must not be processed by the drives.
According to the PROFIBUS Profile (Lit [2] ) the ramp generator can be enabled by sett ing bit 5 of COMMAND
WORD 1 to a "1" v alue.
In t his case the host system has to transmit t he following inf ormat ion in the BROA DCAST ENABLE ARRAY:
Word a = 0000 0000 0000 0011 (Broadcast Flag set and
PROCESS DATA WORD 1
(= COMMAND WORD 1)
enabled)
Word b = 0000 0000 0010 0000 (Command Bit 5 enabled)
Words c to d = 0000 0000 0000 0000
Remarks on t he Bro adcast Tel egram:
- Broadcast T elegrams are only possible wit h telegram ty pes containing a PARAMETER DATA area (e. g.
PROFIBUS Adjustable-S peed Dr iv es P r ofile , P P O t y pes 1, 2 or 5)
- For a double- wor d RE F VA LUE ( 32 bit inf or m ation) the Enable B its of bot h: High W or d and LOW Word have
commonly to be set or r es et by the mas ter s tat ion.
Appendix
Specification, USS protocol Appendix - 5
E20125-D0001-S302-A1-7600
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