Communication Procedure - Siemens SINAMICS G130 Operating Instructions Manual

Operation
6.11 Communication via MODBUS TCP
Table 6- 63 Response for successful write operation
Value Byte Description
MBAP header
Number of following data bytes (20 h: 32 bytes ≙ 16 registers)
03 h 7 Function code (read)
20 h 8
0002 h 9,10 40601: DS47 Control = 2 (request was executed)
2F04 h 11,12 40602: Function code 2F h (47), response length 4 bytes
8002 h 13,14 40603: Request reference mirrored = 80 h,
response identifier = 2 (change parameter)
0101 h 15,16 40604: DO-ID = 1, number of parameters = 1
Table 6- 64 Response for unsuccessful write operation - write request still not completed
Value Byte Description
MBAP header
Number of following data bytes (20 h: 32 bytes ≙ 16 registers)
03 h 7 Function code (read)
20 h 8
0001 h 9,10 40601: DS47 Control = 1 (request is processed)
2F00 h 11,12 40602: Function 2F h(47), response length 0 (fault)
0004 h 13,14 40603: Error code: 0004 Response Not Ready (response has still not been
issued)
6.11.7

Communication procedure

Logical error
If the slave detects a logical error within a request, it responds to the master with an
"exception response". In the response, the slave sets the highest bit in the function code to
1. If the slave receives, for example, an unsupported function code from the master, the
slave responds with an "exception response" with code 01 (Illegal function code).
Table 6- 65
Exception
code
01
02
03
04
310
Overview of exception codes
Modbus name
Illegal function code
Illegal Data Address
Illegal data value
Server failure
Remark
An unknown (unsupported) function code was sent to the
slave.
An invalid address was requested.
An invalid data value was detected.
Slave has terminated during processing.
Operating Instructions, 07/2016, A5E00331449A
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