Siemens Simatic M7-400 Reference Manual page 586

Diagnostic Data of the Signal Modules
Bytes 11 to 42 of the SM 422; DO 32
Data record 1 with bytes 11 to 42 contains the channel-specific diagnostic data.
The figure below shows the assignment of the diagnostic byte for a channel of the
module.
Figure B-13
Bytes 2 and 3 of the SM 422; DO 16
Byte 2
Byte 3
Figure B-14
B-12
24 VDC/0.5 A
7 6 5 4 3 2 1 0
0 0 0
Configuring/parameter assignment error
Short-circuit to L+
Short-circuit to M
Wire break
External auxiliary supply missing
Diagnostic Byte for a Channel of the SM 422; DO 32 x 24 VDC/0.5 A
20-120 VAC/2 A
7 6 5 4 3 2 1 0
0 0
0 0 0 0 0
Operating status 0: RUN
7 6 5 4 3 2 1 0
0
0 0 0 0 0 0
EPROM error
Bytes 2 and 3 of the Diagnostic Data of the SM 422; DO 16 x 20-120 VAC/2 A
S7-400, M7-400 Programmable Controllers Module Specifications
1: STOP
A5E00069467-07