Siemens sinamics dcp - Page 284

Operation
7.7 Communication via Modbus TCP
SINAMICS DCP
282 Operating Instructions, 09/2019, A5E34382853K
Structure of a write request via Modbus function code 06 (FC 06)
Start address is the holding register address.
Via FC 06, with one request, only precisely one register can be addressed. The value, which
is written to the addressed register, is contained in bytes 10 and 11 of the write request.
Table 7- 38 Structure of a write request for device number 17, example
Value
Byte
Description
MBAP header
06 h
00 h
63 h
55 h
66 h
7
8
9
10
11
Function code
Register start address "High" (write register 40100)
Register start address "Low"
Register data "High"
Register data "Low"
The response returns register address (bytes 8 and 9) and the value (bytes 10 and 11),
which the higher-level control had written to the register.
Table 7- 39 Device response to the write request, example
Value
Byte
Description
MBAP header
06 h
00 h
63 h
55 h
66 h
7
8
9
10
11
Function code
Register start address "High"
Register start address "Low"
Register data "High"
Register data "Low"
Table 7- 40 Invalid write request
Write request
Inverter response
Incorrect address (a holding register address does not exist) Exception Code 02 - invalid data
address
Write to a "read-only" register Exception Code 04 - device failure
Write to a reserved register
For Exception Code 4, via the holding register 40499, you can read out the internal drive
error code, which has occurred for the last parameter access via the holding register.