Siemens SIMATIC ET 200pro Operating Instructions Manual page 117

Interrupts, diagnostics, error messages and system events
11.1 Status and error display of the CPU
Meaning of the RUN/STOP, ERROR and MAINTENANCE LEDs
The CPU 1516pro-2 PN has three LEDs for displaying the current operating state and
diagnostic status. The following table shows the meaning of the various combinations of
colors of the RUN/STOP, ERROR and MAINTENANCE LEDs.
Table 11- 1 Meaning of the LEDs
RUN/STOP LED
LED off
LED off
LED lit green
LED lit green
LED lit green
LED lit green
LED lit green
LED lit yellow
LED lit yellow
LED lit yellow
LED lit yellow
LED flashes yellow
LED flashes
yellow/green
LED flashes
yellow/green
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ERROR LED MAINTENANCE LED
LED off
LED flashes red
LED off
LED flashes red
LED off LED lit yellow
LED off
LED flashes yellow
LED flashes red
LED flashes red
LED off
LED flashes yellow
LED off
LED flashes red LED flashes yellow
LED off
LED off
LED flashes red LED flashes yellow
Missing or insufficient power supply on the CPU.
LED off
An error has occurred.
LED off
CPU is in RUN mode.
LED off
A diagnostics event is pending.
LED off
Maintenance demanded for the plant.
The affected hardware must be
checked/exchanged within a short period.
Active Force job
Bad configuration
An error has occurred.
LED off
LED off
Firmware update successfully completed.
CPU is in STOP mode.
LED off
The program on the SIMATIC memory card is
causing an error.
CPU defective
CPU is performing internal activities during STOP,
e.g. startup after STOP.
LED off
Download of the user program from the SIMATIC
memory card
Startup (transition from RUN → STOP)
LED off
Startup (CPU booting)
Test of LEDs during startup, inserting a module.
LED flashing test
Operating Instructions, 11/2019, A5E35873416-AC
Meaning
CPU 1516pro-2 PN (6ES7516-2PN00-0AB0)