Please explain brief history of problem along with snap of NCU 7 segment display display & alarm message screen on OP.

Significance of display is PLC watchdog eroor is detected & PLC is in STOP mode. Have you tried PLC resest? (before reseting PLC confirm you have valid PLC back up data,)

If yes & even problem persist, please go on line & check PLC diagnostic buffer. You can save PLC diagnostic buffer file in text format & attach here for further trouble shooting.

It's always good idea to have NC/PLC back before something happen,  in your situation if did not make PLC back up, that will be bad news for you--it is too later to make it. Do you have have Alarm 120202 like Waiting for Connect NCK or No communication to PLC? Do you have PC/PG with Siemens SIMATIC Manage , try to communicate with MPI to upload PLC Back up?

I don't think you can get communication to PLC.

to save your NCU, try your luck like this :

shut off power--->remove all connectors from NCU, power up to see , if there is the same situation .

Power off and set S4 on NCU to "3" then power up NCU. to see you can get PF LED on and PS Led slow flashing, the bring S4 to "2" the back to "3" to clean the PLC, after PLC only has PS led on, set S4 to 0 , you should save your NCU.

give some feedback

CNC Chennai

HI Attached the Video File  of the Error 

NCU 573.2