Siemens S5 cpu problem

MagCarb

Guest
M
I have Siemens S5 6ES5 942-7UB11 fitted with a 6ES5 375-0LA21 EPROM, Analog I/O card and 6 digital I/O that crashes recently. I reboot the controls and it's ok for a few minutes then crashes again.

Since the machine was originally from germany, we have no backup copy of the program. I plugged in my computer running S5 v7.17, to upload the program and download it again, still theres error.

I've tried "Overall default/reset" procedure alot of times with the Eprom connected and still i can't get the error to go away. I tried overall reset w/out the eprom and the RUN led turns green but the programs still not responding. I called up Siemens technician and give me advice in how to transfer Eprom program to CPU ram but still theirs error.

My questions are

1. How can i get to transfer EPROM program to the CPU RAM?

2. Why my pc running STEP5 cant upload program from Eprom? The siemens tech told me that i have to upload program from eprom using the PG programmer?

3. When i uploaded the program using S5 and save it, then downloaded it again, i get memory full error during downloading? Why is that?
 
As far as your error, try this> Once you have siemens open go to >plc>plc info Istack. This brings up I stack screen 1. Press F1 continue. This is Istack screen 2. Look down at the bottom, if you see continue, press it again to go to screen 3. What this screen shows you is open data block, open function block, and open programming block when the fault occurs. The real sac is a relative step address counter, it shows you the next step to be executed. The real sac will be in octal. Note: Make sure you go to the i-stack when your plc is faulted, this is the only time it is avalible.
 
1. How can i get to transfer EPROM program to the CPU RAM?

If there is no battery in the PLC the program will be loaded fom EPROM into PLC ram whenever you power off and on.

2. Why my pc running STEP5 cant upload program from Eprom? The siemens tech told me that i have to upload program from eprom using the PG programmer?

To READ the EPROM directly (and to BLOW it) you will need a Siemens Programmer . It has a slot to plug in the EPROM. However by connecting your laptop you can "LOAD" the program from the PLC into the laptop.

3. When i uploaded the program using S5 and save it, then downloaded it again, i get memory full error during downloading? Why is that?

Did you try and load the program into the PLC with the EPROM plugged in?

Where are you?
Please email with more details if you still have problems
 
Magcarb

If you preform the following steps this will reload the progam from the eeprom.

set the CPU to stop mode
set and hold the 'default/overall reset' button into the or position.
switch the CPU selector switch twice from 'ST' to 'RN'
The stop LED will momentarily go off.
release the overall reset switch and the CPU will no have preformed an overall reset and re-read the program from the eeprom.

One point to note is that when the PL has an eeprom inserted you cannot edit the program online while the eeprom is in

Paul
 
I did try what Moggie and Mike advice but it still the same.

Moggie, how long will the loading from eprom to cpu ram when battery is pulled out? and what will be the indication that the program is successfully transfered to the cpu ram? The ST led just keep on blinking.

Paul, i did overall reset a couple of times, but still Cpu not responding, RN Led just turn on for a few second then off again.
 
Magcarb

If you follow my previous post step by step then this will definately load the program from the eeprom.

You do have to move the stop/ run switch twice from stop to run.

If your eeprom has a fully functioning program in it then this should work.

You could try going online with your step5 software and deleting the entire PLC and then following my post.

Before you delete the PLC it might be prudent to transfer all the blocks from the PLC to your PC.

Paul
 
I think that the only option now is to look at the Stacks (I Stack and B Stack) to see what the problem is.

Pease send me your email address.
 
First verify the CPU is OK. Power down and remove the Eeprom, hold the spring loaded switch down with the left hand and cycle the RUN/STOP switch 3 times. (Overall reset) Then go RUN/STOP again. It should come up to run without a program and without a hardware config. If not, the CPU is bad, doughtful though. My guess is the PIW or PQW that you are writing to is not there. In your laptop, search the program for PIW's and PQW's. If you REM them out (with //) and download the blocks, it should stay running. If it faults during download, cycle one time stop/run.

The eeprom can be UPLOADED by having it in the slot and UPLOADING to the software on your laptop. Then removing the EEPROM, by re-downloading to the PLC you will have the program control in your laptop, and RAM make changes etc.
The S5-942 CPU cannot store it's program onto a EEprom without an external burner.
 
Isnt this suppose to be an open forum where all problems and options are discussed "openly"?

If that is so then why would an email address be necessary?

The idea I believe is to discuss issues where many can see the problem and hopefully the solution.

Please make an effort to discuss topics on the forum and not via email specifically.
 
rsdoran is right. Please keep the discussion on these pages. There are many of us watching that are not so familiar with the siemens PLC's.
Things like this crop up in the field and it would be good to see this to a satisfactory conclusion.
 
MagCarb,

the mentioned CPU is one from the S5-115U family. In this family the memory module (be it RAM, EPROM or EEPROM) is an extension to the internal RAM memory and not a backup as with the S5-100U family. Therefore the contents of the EPROM are NOT copied into the RAM.

I strongly advise to check the blackening of the EPROM window. If the window isn't covered entirely with a lightshielding tag, it is possible the contents of the EPROM are changed. The construction of these PLC's is open to enable airflow for cooling. But if the air can pass through, so can light! And even a simple TL tube gives enough UV out to damage EPROMs over a certain period of time.

I once had the same problem, but it was caused by damage of the system EPROM (same reason as described). Luckily I had a second, identical, CPU so I could copy the system EPROM. This CPU runs about 4 years now without a problem since.

To copy the contents of a Siemens EPROM, you need a PG from Siemens or a special EPROMMER from Siemens. It is not possible to copy them through the CPU, unless its a S5-100U.

With a S5-100U you can copy, but you're limited to a 16kB EPROM. If you copy from the PLC to the EPROM, you take the build-in blocks with the program. These will not work with a CPU from a different family. So, this is also not a solution!

Concerning the memory full problem: Siemens does NOT overwrite the program already in the CPU, although it says so. What happens if you download a block to the CPU is the following:
  • if no block is present with the same name, the block is entered in the memory.
  • if there is already a block in the CPU with the same name, this block is declared invalid. The downloaded block is entered in the memory at the first avaliable space.
If you want to remove the invalid blocks, you have to compress the PLC memory. In my version of STEP5 I choose PLC - Compress PLC Memory (Ctrl+Shift+F2). Remember: this happens nly in the RAM part of the memory, which is only 10kB or 5k instructions for the CPU942. The EPROM can be as big as 32kB or 16k instructions.

The RAM memory in the S5-115U family is mostly only used for storing variable data in datablocks. The program is usualy stored in the EPROM. That's the reason why I direct you to the EPROM as the cause for trouble.

Kind regards,

Jean Pierre Vandecandelaere
Instructor PLC - SCADA
VDAB Bruges
Belgium
 

Procedure to transfer the program to cpu




1. Switch off the CPU card and remove the EPROM



2. Power off the PLC



3. Plug out the CPU card from mother board



4. Plug in the CPU card again after 10 secs



5. Power on the PLC and CPU card



6. start the S5 program



7. change ->further->SINEC NCM COMS



8. Go to CPU functions



9. Select Delete CPU database



10. Select Edit and then go to CPU Init



11. Enter the Mac ID at the corresponding PLC and then say OK



12. Go to File -> select ->select file name-> PLC epromprogram



13. Go to transfer and click FD->CP and select total (F2)
 
Rajesh,

after almost three years of inactivity on this thread, I gues the problem has been resolved already long time ago. There's absolutely no need to revive this thread.

Kind regards,
 
Similar problem with cpu 942

Dear all,
i know the thread has been closed years ago, but i am experiencing almost same problem.
As happens to several engineers to follow companies relocations in mainland China, i have to face problems with machines that i never saw before.
I am used to work and develope software for AB SLC500 and 5000, Omron, Mitsubishi, GE,Philips, Matsushita, but nobody is perfect...i never used Siemens~~
Well now i am in front of the machine, the plc shows me the problem that has been discusse here years ago, the program is not running. I have tried overall reset and everything was suggested in the forum, is there anybody who might remember something about this problem?

Thanks in advance for any help.
Steve.
 

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