Siemens SIMATIC S7-400 Reference Manual page 422

Diagnostic data of signal modules
B.5 Diagnostic data of the analog input modules as of byte 2
Byte 8
Bytes 9 to 24 of the SM 431; AI 16 x 16 bit
Data record 1 contains the channel-specific diagnostic data, starting at bytes 9 to 24. The figure
below shows the assignment of the diagnostic byte for a channel of the module.
Table B-20
Byte 9-24
Bytes 2 and 3 of the SM 431; AI 8 x RTD x 16 bit
Table B-21
Byte 2
422
Byte Bit
7 Channel error 15
6 Channel error 14
5 ...
4 ...
3 ...
2 ...
1 Channel error 9
0 Channel error 8
Diagnostic byte for a channel of the SM 431; AI 16 x 16 bit
Byte Bit
7 Overflow
6 Underflow
5 Reference channel error
4 Wire break
3 Short-circuit to M
2 0
1 0
0 Configuring/parameter assignment error
Bytes 2 and 3 of the diagnostic data of the SM 431; AI 8 x RTD x 16 bit
Byte Bit
7 0
6 0
5 0
4 0
3 0
2 Operating mode 0: RUN; 1: STOP
1 0
0 0
Meaning
Meaning
Meaning
S7-400 Automation System Module Data
Reference Manual, Ausgabe 11/2016, A5E00850736-08