Diagnostic Data of the Signal Modules
B-8 S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
B.4 Diagnostic Data of the Digital Output Modules
as of Byte 2
The structure and contents of the different bytes of the diagnostic data for special
digital output modules are described below. The following general rule applies:
When an error occurs, the bit concerned is set to ”1”.
You will find a description of possible error causes and appropriate remedies in the
section called on the special module.

Bytes 2 and 3 of the SM 422; DO 16 20-125 VDC/1.5 A

Byte 2
76 0
Operating status 0: RUN
1: STOP
54321
0
Byte 3
76 0
EPROM error
54321
0
0
000 0
000 000
0
Figure B-8 Bytes 2 and 3 of the Diagnostic Data of the SM 422;
DO 16 x 20-125 VDC/1.5 A