Siemens SIMATIC S7-1500 Operating Instructions Manual page 87

Meaning of the LED displays
The CPU has three LEDs to indicate the current operating mode and diagnostic status. The
following table shows the meaning of the various combinations of colors for the RUN/STOP,
ERROR and MAINT LEDs.
Table 9- 1
RUN/STOP
LED green
LED green
LED green
LED green
LED green
LED yellow
LED yellow
LED yellow
LED flashes
LED flashes
CPU 1505SP (F) Ready4Linux Version 2.7
Operating Instructions, 05/2019, A5E46864285-AA
Meaning of the LEDs
ERROR LED
LED
LED off LED off
LED off
LED flashes
red
LED off
LED off
LED flashes
red
LED flashes
red
LED off
LED flashes
red
LED off
yellow
LED off
yellow
Interrupts, error messages and diagnostics and system alarms
MAINT LED
POWER OFF, the DIAG LED dis-
play is not enabled.
LED off
CPU is in RUN mode.
LED off
A diagnostics event is pending.
LED off
Maintenance demanded for the
plant.
LED yellow
The affected hardware must be
replaced within a short period of
time.
For fail-safe CPU:
Safety mode is deactivated.
Maintenance required for the plant.
The affected hardware must be
LED flashes
replaced within a reasonable time
yellow
period.
An error has occurred.
LED off
LED off
CPU is in STOP mode.
LED off
The user program causes an error.
CPU is in FAULTED status.
LED flashes
yellow
CPU is performing internal activi-
ties during STOP, e.g. ramp-up
LED off
after STOP.
Loading the user program.
CPU is in HOLD state.
A programmed breakpoint in the
LED off
user program has been reached.
9.1 Status and error display of the CPU
Meaning
87