Siemens Simatic M7-400 Reference Manual page 579

Bytes 4 to 8 of the SM 421; DI 16
Byte 4
Byte 5
Byte 6
Byte 7
Byte 8
Figure B-3
Bytes 9 to 24 of the SM 421; DI 16
Data record 1 with bytes 9 to 24 contains the channel-specific diagnostic data. The
figure below shows the assignment of the diagnostic byte for a channel of the
module.
Figure B-4
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
24 VDC
7 6 5 4 3 2 1 0
0
Channel type B#16#70: digital input
7 0
7 0
7 6 5 4 3 2 1 0
Channel error, channel 0
Channel error, channel 1
...
Channel error, channel 6
Channel error, channel 7
7 6 5 4 3 2 1 0
Channel error, channel 8
Channel error, channel 9
...
Channel error, channel 14
Channel error, channel 15
Bytes 4 to 8 of the Diagnostic Data of the SM 421; DI 16 x 24 VDC
24 VDC
7 6 5 4 3 2 1 0
0 0 0 0 0
Configuring/parameter assignment error
Wire break
Sensor supply missing
Diagnostic Byte for a Channel of the SM 421; DI 16 x 24 VDC
Diagnostic Data of the Signal Modules
Number of diagnostics bits that the module
outputs per channel: 8 bits long
Number of channels of the same
type in one module: 16 channels
B-5