Challenging problem!! Simatic S5 cpu 928b run not

Hi Experts,

We have a problem here with the Simatic S5 CPU 928B which doesnt go into RUN mode.
Machine was not in use for over a year and my employers decided to start and run the machine now. Power was switched ON and everything else seems alright except that the CPU's LED wouldnt get green.
An overall reset would get the ADF error LED ON.

Machine control system is configured as
One central controller(with CPU 928B) and 2 Expansion Units.
Communication is through the interfaces 304 and 314.
Had communication and battery issues. Hence changed the power supplies of CC and a EU with new fans and batteries.
No red LED on IM304/IM314.
Have been able to check all the interface cards by swapping them with new cards from stock.
Program is available on RAM and laptop.
Have been able to delete the program from the CPU but the CPU wouldnt accept the blocks transfer while while trying to upload the program.
As this sounded like a CPU memory problem. I have deleted all the data from the CPU, disconnected all the I/Os and and tried to get it in run mode by doing an overall reset and a reset but the stop LED still blinks.

Any suggestions and hints welcome.
Photos of Istack - ADF error and PLC attached.

It seems that there is still a program in the CPU. Istack shows an address failure in PB1 with the relative step address counter at address 1. The step address counter is incremented before an instruction is executed so it indicates that the problem occurred on the previous instruction i.e. 0. The very first instruction in PB1.

An overall reset should clear the memory and leave the CPU in stop with the red stop LED lit but not flashing. The CPU should then go in to run with no program installed and give you a green led.

One other thing you might try is to go online, force the CPU to stop (solid red stop LED) and then force a cold restrart.

Good luck,

Nick

Hi Nick,
Thanks for the reply.
I have deleted the CPU a couple of times using PG2000. But the CPU stop LED would just Flash. I have reinserted the RAM and Overall Resetted with all the I/Os in. It comes back with the same ADF error and Istack pointing toward PB01 line0.

Have attached the screenshots of PB01 .

Regards
Kal

Hi Nick,

I have tried the cold restart but the CPU doesnt permit.
Comes up with the messge " PLC in STOP Mode".

Stop LED still flashing.

Screenshots attached.

If you have successfully done an overall reset then the stop led should be solid on and not flashing. Having done this, and before reloading a program, you should be able to flick the stop/run switch to run and the PLC should then go in to run.

Is it possible that the ram module is faulty? Try removing it, do an overall reset and flick the CPU to run.

Hi Nick,
I have taken the ram out and done an overall reset. It's still the same thing.
I have also tried a new CPU from stock and it does the same.

See attached extracts from the S5-135 manual.

Nick

The pictures ore from the 948 section of the manual

From the 928B section of the manual

Nick

Hi Nick,

Thought i should mention, The other thing which I am not able to do is delete or transfer blocks from the PG to PLC. The only way I am able to delete the program from the CPU is by taking the EEPROM out and performing an overall reset of the CPU.

Whenever i try to overwrite a block. It would come up with a message of memory being full and memory to be compressed and when i click OK it comes back with an error " No communication with PLC".
This is the issue with the old CPU and also the new CPU from stock.
Any ideas???

if the program is in EEprom then you cannot clear it via the CPU but that shouldn't be a problem as the program in the EEprom is unlikely to be corrupted.

I'm not familliar with PG2000 as i've never used it. But you need to be able to get the CPU in a consistent state where it will go in to run without a program loaded. Remove the EEPROM, Put the CPU in stop state (red light solid on) Overall reset if necessary.

Once you can get the CPU in run with no program loaded then you can proceed.

Power down the PLC, replace the EEprom, leave the CPU switched to stop, power up the CPU, download whatever blocks are not stored in the EEPROM (normally datablocks). Switch the CPU to run; if it does not start then go online and force a stop (red light solid on) and then force a cold start.

If that doesn't do it then I'm out of ideas.

Nick

Hi Nick,

Thanks for your help. All your suggestions have been useful in troubleshooting so far.

Have found out a few things about the CPU I am using. Its a CPU 928B, has 16KB dual port RAM and cannot be operated with an EEPROM. EEPROM is like an extended memory for this CPU.

You are right, I am not able to delete the data as it is in the EEPROM.

Luckily, I have a found an old spare EEPROM(without data) in the store and have used it along with the spare CPU and the CPU went into a RUN state after an overall reset.
This puts my doubts about the CPU and EEPROM to rest. Looks like the EEPROM and CPU are good.

I have now been able to transfer all the blocks into the CPU and tried to RUN.
it comes up with an ADF error as before....suggesting we have a hardware error.
Guess have to start looking for a faulty I/O again.
I have tried swapping the existing I/Os with new ones but no joy.
Any new ideas, how to find faulty hardware??

Attached is my Istack and PB01 screenshot.

Correction:
Have found out a few things about the CPU I am using. Its a CPU 928B, has 16KB dual port RAM and cannot be operated without an EEPROM. EEPROM is like an extended memory for this CPU.

Hi!

Firstly; check the card with the input byte 24, if the enable-voltage (Freigabe) is present on the respective terminals.

Secondly; check if the dip-switches on that card are set correctly, and that the setting is exclusive for that input card. (An output card is allowed to have the same address).

Kalle

??? In the picture of your expansion unit EU1 I cannot see any communication cards, but only IOs. Please explain.

Kalle

Hi Kalle