Siemens SIMATIC S7-1500 Manual page 49

Interrupts, error messages, diagnostics and system alarms
4.1 Status and error display of the CPU
Meaning of the RUN/STOP, ERROR and MAINT LEDs
The CPU 1518-4 PN/DP MFP has three LEDs for displaying the current operating mode and
diagnostics status. The following table shows the meaning of the various combinations of
colors for the RUN/STOP, ERROR and MAINT LEDs.
Table 4- 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 yellow
LED lit yellow
LED lit yellow
LED lit yellow
LED flashes yellow
LED flashes
yellow/green
LED flashes
yellow/green
48
ERROR 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 off
LED flashes yellow
LED off
LED flashes red LED flashes yellow
LED off
LED off
LED flashes red LED flashes yellow
MAINT LED
Missing or insufficient power supply on the CPU.
LED off
An error has occurred.
LED off
CPU is in RUN mode.
There are no events, requirements, errors, etc.
LED off
A diagnostics event is pending.
LED off
Maintenance demanded for the plant.
You need to check/replace the affected hardware
within a short period of time.
Active Force job
Bad configuration
A diagnostics event is pending.
LED off
Firmware update successfully completed.
CPU is in STOP mode.
LED off
The program on the SIMATIC memory card is caus-
ing an error.
Firmware update using SIMATIC memory card has
failed.
The CPU has detected an error state. Additional
information is available via the CPU diagnostic
buffer.
CPU is performing internal activities during STOP,
e.g. startup after STOP.
LED off
Download of the user program from the SIMATIC
memory card
CPU executes a program with an enabled break-
point.
Startup (transition from STOP → RUN)
LED off
Startup (CPU booting)
Test of LEDs during startup, inserting a module.
LED flashing test
Meaning
CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)
Equipment Manual, 07/2021, A5E40882737-AB