Siemens SINAMICS G120P, Operating Instructions Manual

Page: 222 / 496

Operation
6.8 Communication via RS485
Inverter cabinet units
222
Operating Instructions, 12/2014, A5E32923362A
6.8.2.4 USS parameter channel (PIV)
Structure of the parameter channel
Depending on the setting in p2023, the parameter channel has a fixed length of three or four
words, or a variable length, depending on the length of the data to be transferred.
The 1st and 2nd words contain the parameter number, the index and the type of job (read or
write). The other words of the parameter channel contain parameter contents. The
parameter contents can be 8-bit values, 16-bit values (e.g. baud rate) or 32-bit values (e.g.
CO parameters). The parameter contents are entered right-justified in the word with the
highest number. Words that are not required are assigned 0.
Bit 11 in the 1st word is reserved and is always assigned 0.
The diagram shows a parameter channel that is four words long.
You can find examples of telegrams at the end of this section.
Request and response IDs
Bits 12 to 15 of the 1st word of the parameter channel contain the request and response
identifier.
Table 6- 14 Request identifiers, controller → inverter
Request identi-
fier
Description Response identifier
positive negative
0 No request 0 7 / 8
1 Request parameter value 1 / 2 7 / 8
2 Change parameter value (word) 1 7 / 8
3 Change parameter value (double word) 2 7 / 8
4 Request descriptive element
1)
3 7 / 8
6
2)
Request parameter value (field)
1)
4 / 5 7 / 8
7
2)
Change parameter value (field, word)
1)
4 7 / 8
8
2)
Change parameter value (field, double word)
1)
5 7 / 8
9 Request number of field elements 6 7 / 8
1)
The required element of the parameter is specified in IND (2nd word).
2) The following request IDs are identical: 1 ≡ 6, 2 ≡ 7, 3 ≡ 8.
We recommend that you use identifiers 6, 7, and 8.