Siemens S7-1200 System Manual page 784

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Table of Contents

Online and diagnostic tools

14.1 Status LEDs

Maintenance requested

Defective hardware

LED test or defective CPU

Unknown or incompatible

version of CPU configuration

"Unknown or incompatible version of CPU configuration" error

Attempting to download an S7-1200 V3.0 program to an S7-1200 V4.0 CPU causes a CPU

error, and the CPU displays a corresponding error message in the diagnostic buffer. If you

reached this state by using an invalid version program transfer card (Page 127), then

remove the card, perform a STOP to RUN transition, a memory reset (MRES) or cycle

power. If you reach this state by an invalid program download, reset the CPU to factory

settings (Page 789). After you recover the CPU from the error condition, you can download a

valid V4.0 CPU program.

The CPU also provides two LEDs that indicate the status of the PROFINET communications.

Open the bottom terminal block cover to view the PROFINET LEDs.

● Link (green) turns on to indicate a successful connection

● Rx/Tx (yellow) turns on to indicate transmission activity

The CPU and each digital signal module (SM) provide an I/O Channel LED for each of the

digital inputs and outputs. The I/O Channel (green) turns on or off to indicate the state of the

individual input or output.

S7-1200 behavior following a fatal error

If the CPU firmware detects a fatal error it attempts a defect-mode restart, and if successful,

signals the defective mode by continually flashing the STOP/RUN, ERROR and MAINT

LEDs. The user program and hardware configuration are not loaded following the defect-

mode restart.

If the CPU successfully completes the defect-mode restart, the CPU and signal board

outputs are set to 0, and the outputs of central rack signal modules and distributed I/O are

set to the configured "Reaction to CPU STOP".

Battery replacement

required (if battery board

Yellow / Green

On (either yellow or green)

(alternating yellow and green)

S7-1200 Programmable controller

System Manual, 03/2014, A5E02486680-AG