Siemens SIMATIC S7-1500 Manual page 22

Error and system messages
Meaning of the LED displays for RUN/ERROR/(MAINT)
LED
RUN ERROR
Off Off
Flashes Off
On Off
On Flashes
1) Information on startup and diagnostics of the communication module is available in the
function manual CM PtP - Configurations for point-to-point connections
(http://support.automation.siemens.com/WW/view/en/59057093).
Meaning of LED displays for TXD/RXD (under the front panel)
LED
TXD RXD
Flashes Off
Off Flashes
22
MAINT
Supply voltage not present or too low at
communication module
Off
CM in startup, parameters not assigned
yet
Off
CM configured and ready for operation
Off
Group error (at least one error pending) Evaluate the diagnostics data and
Off
Meaning
Interface is transmitting
Interface is receiving
Meaning
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CM PtP RS422/485 BA communication module (6ES7540‑1AB00‑0AA0)
Solution
Check the power supply of the station.
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eliminate the error.
1)
Solution
Manual, 01/2013, A5E03777484-01