RUN/STOP LED
LED off
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
CPU 1516T-3 PN/DP (6ES7516-3TN00-0AB0)
Equipment Manual, 11/2022, A5E40898375-AC
ERROR LED
LED flashes red
LED off
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
Interrupts, error messages, diagnostics and system alarms
MAINT LED
An error has occurred.
LED off
CPU is in RUN mode.
LED off
Maintenance demanded for the plant.
The affected hardware must be checked/replaced
within a short period of time.
Active Force job
OPC UA server of the CPU expects initial trust lists
and CRLs via GDS Push function.
Bad configuration
A diagnostics event is pending.
LED off
Firmware update using SIMATIC memory card suc
cessfully completed.
CPU is in STOP mode.
LED off
CPU runs a program with active breakpoints. The
program is at a breakpoint.
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 buf
fer.
CPU is performing internal activities during STOP,
LED off
e.g. startup after STOP.
Download of the user program from the SIMATIC
memory card
CPU carries out a program with active breakpoint.
The program is presently moving from one break
point to another.
Firmware update is being performed.
Startup (transition from STOP → RUN)
LED off
Startup (CPU booting)
Test of LEDs during startup, inserting a module.
LED flashing test
5.1 Status and error display of the CPU
Meaning
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