Siemens SINAMICS V20 Operating Instructions Manual page 187

Response for unsuccessful write operation - write request still not completed
Value
11 h 1
03 h
20 h
0001 h
2F00 h
0004 h
xx h
xx h
Exception Responses
If an error is detected through the MODBUS processing, the slave will respond with the FC
of the request, but with most significant bit of the FC high and with the Exception Code in the
data field. However, any error detected on the global address 0 does not result in a response
since all slaves cannot respond at once.
If an error is detected within the received message (for example, parity error, incorrect CRC
and so on), then NO response is sent to the master.
Note that if a request with FC16 is received which contains a write that the converter cannot
perform (including write to a zero entry), other valid writes will still be performed even though
an exception response is returned.
The following MODBUS Exception Codes are supported by SINAMICS V20:
Exception Code
01
02
03
04
The table below shows the cases in which an Exception Code is returned:
Error description
Unknown Function Code
Read registers, which are out of boundary
Write register, which is out of boundary
Read request of too many registers (>125)
Write request of too many registers (>123)
Incorrect message length
Write to a read-only register
Write register, error in parameter access
Read register, error in Parameter Manager
Write to a zero entry
Unknown error
SINAMICS V20 Converter
Operating Instructions, 10/2019, A5E34559884-012
Byte Description
Slave address
Number of following data bytes (20 h: 32 bytes ≙ 16 regis-
2 Function code (read)
3
ters)
4,5 40601: DS47 Control = 1 (request is processed)
6,7 40602: Function 2F h(47), response length 0 (fault)
8,9 40603: Error code:
still not been issued)
10 CRC "Low"
11 CRC "High"
MODBUS name
Illegal function code
Illegal data address
Illegal data value
Slave device failure
7.2 MODBUS communication
0004 Response Not Ready (response has
Meaning
The function code is not supported – only FC3, FC6 and
FC16 are supported.
An invalid address was queried.
An invalid data value was recognized.
An unrecoverable error occurred while the device was
processing the action.
Exception Code
01
02
02
03
03
03
04
04
04
04
04
Communicating with the PLC
185