Simatic S7-313 CPU fault


Thread Starter

Mr. Patrick So

We have a system use S7-313 CPU (MPI) communication with CP5412A2 and a RS485 repeater between CPU and CP card. S7-313 CPU CP5412A2 RS485 repater Simatic Net S7-Profibus The problem is all LEDs of 313 CPU will flashing after a period of irregular time and we found the following event into the STEP 7 ver. 5.0 "Diagnosis Buffer". Event: DEFECTIVE: internal system error EVent ID: 16#4550 Detail on Event: DEFECTIVE : internal system error No relevance for user (Z1) : 7190 Previous operating mode : RUN Requested operation mode : DEFECTIVE Internal error, Incoming event
Hello Patrick, I had a similar problem with early versions of 414 CPU in 1998: all the LED were flashing, program was gone and there was no way to communicate with the CPU. A deep investigation revealed that spikes and other nasty disturbs on MPI line were somehow accepted as kind of illegal commands by the CPU (the MPI port is the programming port!), messing the memory. I had problems even connecting or disconnecting the programming computer MPI plug (the CPU often changed unexpectedly to STOP mode). Check your CPU firmware and update to the latest release. I suggest also to check your MPI line for bad/loose connections. You may also take a look to the Siemens Knowledge Manager at regards Luca Gallina [email protected]
It sounds as if your CPU unit may be defective, or if powered by a seperate 24V dC supply check this ut for current limiting. I had a similar fault on the same CPU recently and we swapped it out to cure the fault. I have sent this unit for repair, but i am still awaiting a response to this, so I can not give any further info.