Siemens SIMATIC S7-1500 Manual page 26

Interrupts, diagnostics, error, and system messages
4.1 Status and error display of the CPU
Meaning of the RUN/STOP, ERROR and MAINT LED
CPU 1511-1 PN has three LEDs to signal the current operating status and diagnostic status.
The following table shows the meaning of the various combinations of colors for the
RUN/STOP, ERROR and MAINT LEDs.
Table 4- 1
RUN/STOP LED
26
Meaning of the LEDs
ERROR LED
LED off LED off
LED off LED flashes red
LED green LED off
LED green LED flashes red
LED green LED off
LED green LED off
LED yellow LED off
LED yellow LED flashes red
LED flashes LED off
yellow
LED off
LED flashes
yellow/green
LED flashes red
LED flashes
yellow/green
MAINT LED
Missing or insufficient power supply on
the CPU.
LED off
An error has occurred.
LED off
CPU is in RUN mode.
LED off
A diagnostic event is pending.
LED off
Maintenance demanded for the plant.
The affected hardware must be replaced
LED yellow
within a short period of time.
Maintenance required for the plant.
The affected hardware must be replaced
LED flashes
within a reasonable time period.
yellow
Firmware update successfully
completed.
CPU is in STOP mode.
LED off
The program on the
SIMATIC memory card is causing
LED flashes
an error.
yellow
CPU defective
CPU is performing internal activities
during STOP, e.g. ramp-up after STOP.
LED off
Loading the user program
Startup (transition from RUN → STOP)
LED off
Startup (CPU booting)
Test of LEDs during startup,
LED flashes
inserting a module.
yellow
LED flashing test
Meaning
CPU 1511-1 PN (6ES7511-1AK00-0AB0)
Manual, 01/2013, A5E31264526-AA