Operating Instructions

Communication via RS485
5.3 Communication via USS
Fieldbuses
116 Function Manual, 04/2018, FW V4.7 SP10, A5E34229197B AE
5.3.4
USS parameter channel
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.
1. and 2nd word contain the parameter number and index as well as 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 (such as 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.
AK: Request and response IDs
Bits 12 … 15 of the 1st The parameter channel words contain the request and response
identifier AK.
Table 5- 4 Request identifiers, control → inverter
AK
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.