Request And Response Ids - Siemens SINAMICS V20 Operating Instructions Manual

Communicating with the PLC
6.1 USS communication
The messages are always sent in the following format (half-duplex communication):
● Response delay time: 20 ms
● Start delay time: depends on baud rate (minimum operation time for 2-character string:
0.12 to 2.3 ms)
● Message transfer sequence:
– master polls slave 1, then slave 1 responds
– master polls slave 2, then slave 2 responds
● Fixed framing characters that can not be altered:
– 8 data bits
– 1 parity bit
– 1 or 2 stop bits
Abbreviation
STX
LGE
ADR
1. ...... n.
BCC

Request and response IDs

Request and response IDs are written in bits 12 to 15 of the PKW (parameter ID value) part
of USS telegram.
Request IDs (master → slave)
Request ID Description
0 No request
1 Request parameter value
2 Modify parameter value (word)
3 Modify parameter value (double word)
134
Significance
Start of text
Telegram length
Address
Net characters
Block check character
Length Explanation
ASCII characters 02 hex
1 byte Contains the telegram length
1 byte Contains the slave address and the
telegram type (binary coded)
Each 1 byte Net data, contents are dependent
on the request
1 byte Data security characters
Response ID
positive
0
1/2
1
2
Operating Instructions, 09/2014, A5E34559884
negative
7/8
7/8
7/8
7/8
SINAMICS V20 Inverter