Online And Diagnostic Tools; Status Leds - Siemens S7-1200 System Manual

Online and diagnostic tools

14.1

Status LEDs

The CPU and the I/O modules use LEDs to provide information about either the operational
status of the module or the I/O.
Status LEDs on a CPU
The CPU provides the following status indicators:
● STOP/RUN
● ERROR
● MAINT (Maintenance) flashes whenever you insert a memory card. The CPU then
You can also use the LED instruction (Page 346) to determine the status of the LEDs.
Table 14- 1
Description
Power is off
Startup, self-test, or firmware
update
Stop mode
Run mode
Remove the memory card
Error
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG
– Solid yellow indicates STOP mode
– Solid green indicates RUN mode
– Flashing (alternating green and yellow) indicates that the CPU is in STARTUP mode
– Flashing red indicates an error, such as an internal error in the CPU, a error with the
memory card, or a configuration error (mismatched modules)
– Defective state:
- Solid red indicates defective hardware
- All LEDs flash if the defect is detected in the firmware
changes to STOP mode. After the CPU has changed to STOP mode, perform one of the
following functions to initiate the evaluation of the memory card:
– Change the CPU to RUN mode
– Perform a memory reset (MRES)
– Power-cycle the CPU
Status LEDs for a CPU
STOP/RUN
Yellow / Green
Off
Flashing
(alternating yellow and green)
On (yellow)
On (green)
On (yellow)
On (either yellow or green)
14
ERROR MAINT
Red Yellow
Off Off
- Off
- -
- -
- Flashing
Flashing -
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