Siemens SIMATIC S7-1500 Manual page 29

Interrupts/diagnostics alarms
5.1 Status and error displays
CHx LED
Table 5- 3 CHx status display
LED CHx
Channel disabled
Off
Channel configured and OK.
On
Channel is configured (channel error pending).
Diagnostic alarm: e.g. wire break
On
See also
Diagnostics alarms (Page 31)
28
Meaning Remedy
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Check the wiring.
Disable diagnostics.
Analog Input Module AI 8xU/I HS (6ES7531-7NF10-0AB0)
Manual, 07/2014, A5E03484886-AC