Communication Procedure - Siemens SINAMICS G110M Function Manual

Communication via RS485
5.4 Communication using Modbus RTU
Table 5- 24 Response for successful write operation
Byte Description
Header
11 h 0 Slave address
Number of following data bytes (20 h: 32 bytes ≙ 16 registers)
03 h 1 Function code (read)
20 h 2
User data
0002 h 3,4 40601: DS47 Control = 2 (request was executed)
2F04 h 5,6 40602: Function code 2F h (47), response length 4 bytes
8002 h 7,8 40603: Request reference mirrored = 80 h,
response identifier = 2 (change parameter)
0101 h 9,10 40604: DO-ID = 1, number of parameters = 1
Table 5- 25 Response for unsuccessful write operation - write request still not completed
Byte Description
Header
11 h 0 Slave address
Number of following data bytes (20 h: 32 bytes ≙ 16 registers)
03 h 1 Function code (read)
20 h 2
User data
0001 h 3,4 40601: DS47 Control = 1 (request is processed)
2F00 h 5,6 40602: Function 2F h(47), response length 0 (fault)
0004 h 7,8 40603: Error code:
issued)
5.4.7

Communication procedure

Procedure for communication in a normal case
Normally, the master sends a telegram to a slave (address range 1 ... 247). The slave sends
a response telegram to the master. This response telegram mirrors the function code; the
slave enters its own address in the telegram and so the slave identifies itself with the master.
The slave only processes orders and telegrams which are directly addressed to it.
Communication error
If the slave detects a communication error on receipt (parity, CRC), it does not send a
response to the master (this can lead to "setpoint timeout").
136
0004 Response Not Ready (response has still not been
Function Manual, 01/2016, FW V4.7 SP6, A5E34229197B AC
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