Siemens Simatic S7-400

Byte Bit Meaning
Byte 8 7 Channel error 15
6 Channel error 14
5 ...
4 ...
3 ...
2 ...
1 Channel error 9
0 Channel error 8
Bytes 9 to 24 of the SM 421; DI 16 x DC 24 V
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-5 Diagnostic byte for a channel of the SM 421; DI 16 x DC 24 V
Byte Bit Meaning
Bytes 9 - 24 7 0
6 0
5 Sensor supply missing
4 Wire break
3 0
2 0
1 0
0 Configuring/parameter assignment error
Bytes 2 and 3 of the SM 421; DI 16 x UC 24/60 V
Table B-6 Bytes 2 and 3 of the diagnostic data of the SM 421; DI 16 x UC 24/60 V
Byte Bit Meaning
Byte 2 7 0
6 0
5 0
4 0
3 0
2 Operating mode 0: RUN; 1: STOP
1 0
0 0
Diagnostic data of signal modules
B.3 Diagnostic data of the digital input modules as of byte 2
S7-400 Automation System Module Data
Reference Manual, Ausgabe 11/2016, A5E00850736-08 409