Program could not be erased

  • Thread starter Shamsul Kamar Mohamed Jan
  • Start date
S

Thread Starter

Shamsul Kamar Mohamed Jan

Dear Listers,
I am using Siemens S5-135U with CPU type 928B. An EPROM is provided at its slot for pgm backup. Recently one bit of the PLC output is broken/damaged and I need to do minor modification to assign new available output for
replacement.

I modified the program and did the following to transfer the modified pgm to the PLC:
1. Switched off the PLC and removed the EPROM module.
2. Switched ON back the PLC and transfered the modified pgm to the PLC.
3. A msg "Program Exist in EPROM" appear on the screen and pgm transfer was aborted.
4. Since the first transfer attemp failed, I then performed an overall reset on the PLC followed by manual cold restart to erase contents of the RAM.
5. When I tried to transfer the modified pgm again, the same msg "Program Exist in EPROM" and program transfer was aborted.

My questions, Why I could not upload new pgm into the PLC? EPROM has been removed and Overall Reset was carried out but yet the user program still
exist in EPROM! Appreciate your valuable inputs.


Best Rgds,
Shamsul Kamar
Federal Power Sdn Bhd
 
E
It's been about 5 years since I worked with an S5 (though I only have experience with the S5-115U), but here's what I remember...

I was never successful in going "online" with the PLC (my laptop refused to communicate), so I did my program changes by burning EEPROMS. I'm not
sure that performing an overall reset will clear the RAM contents....I think it just forces the PLC to re-load the EEPROM into RAM. You should be able to just overwrite/modify the program in RAM with the Step5 software. I realize that this is exactly what you're trying to do, but just make sure that you're doing THIS step correctly. You should not have to do an overall reset to get the new program in. The EEPROM isn't causing any grief, since it's not there! ;o) Remember to leave the EEPROM out from now on, so it won't
overwrite your new program. Might be a good time to buy a EEPROM burner to keep this new program for the future?

I'm sure that other list members will have a better answer......

Regards,

- Eric Nelson
[email protected]
Controls/Software
Packaging Associates Automation Inc. [email protected]
Rockaway, NJ, USA
 
D

D.C. Pittendrigh

Hi All

Sorry I missed the original posting but for what its worth heres my 5 cents.

> I was never successful in going "online" with the PLC (my laptop
> refused to communicate), so I did my program changes by burning
> EEPROMS. I'm not sure that performing an overall reset will clear the
> RAM contents....I think

Overall reset clears the DB0 on a 115U, which is the index to the user blocks in memory. The blocks in user memory contain a header which defines them as being valid or not, as far as I know overall reset invalidates all blocks, I don't think it generally overwrites the RAM contents, but as the contents are reduced to
garbage by clearing DB0, it is of little importance what they contain anyway.

> it just forces the PLC to re-load the EEPROM into RAM. You
> should be able to just overwrite/modify the program in RAM with
> the Step5 software. I realize

This is reminiscent of what the 95U does but is certainly not the behaviour of a 115U. The 115U does not copy the blocks into RAM, they are run off the EPROM and if you try to overwrite them, you will get an error message from your programmer I think error code 70, saying Block is valid in Eprom.

> that this is exactly what you're trying to do, but just make sure that
> you're doing THIS step correctly. You should not have to do an
> overall reset to get the new program in. The EEPROM isn't causing
> any grief, since it's not there! ;o) Remember to leave the
> EEPROM out from now on, so it won't overwrite your new
> program. Might be a good time to buy a EEPROM burner to
> keep this new program for the future?

Not being entirely sure of the original question, I would add that the Eprom or Eeprom on a 115U contains program which cannot be overwritten without a separate initiative to reprogram it usually by plugging into your programmer directly. The contents of the Eprom can be transferred into the CPU by plugging the Eprom into the programmer and then carrying out the appropriate management function. They can then
be modified debugged and backed up to the Eprom once again. Having done this the Eprom can be inserted into the CPU and the program is once again secure from unintentional modification

Just be warned that in the 115U, as the Eprom is non-volatile, and is not copied into RAM but run from the Eprom, any DB's with volatile data must be loaded into RAM or the CPU cannot alter them. There are tools available in the S5 instruction set but many programmers are too lazy to use them, to create DB's in RAM on start up, and as a consequence you will often have to back up your
DB's to disk and reload them after resetting the PLC.

Feel free to contact me directly if you have specific questions at EMAIL:[email protected]

Regards
Donald Pittendrigh
 
N

Nick Haddock

The EPROM in a 928b CPU is not for back up it carries the user program. With the EPROM submodule in place the user program cannot be
down loaded from PC or PG. You need to erase and re blow the EPROM with modified program or replace EPROM with a RAM submodule. To make frequent changes to a program you should use a RAM
submodule instead of an EPROM submodule as the RAM sub-module permits online changes.

Another point is that there is RAM on board the CPU but this is for Dynamic data exchange (DB usage). When you overall reset the CPU you delete the DB's in the CPU.( Something you should be aware of if you don't have a back up program.)

Nick Haddock
 
L

Luc Haverhals

The 928B CPU has some standard Siemens function blocks stored in internal ROM. If you download your program to the CPU, these blocks are also transferred but because these blocks are already in the CPU you will get a message like "Block exist in Eprom, continue or abort". Just press continue for every standard function block and your program should be loaded correctly.

After the transfer you can compare the program in the CPU with the program on your PC. (function F6 if you use Step 5 version 7).

Hope this is of help to you,

Luc Haverhals

Reditech - Belgium
Tel: 0032 3 711 32 93
Fax: 0032 3 711 32 94
[email protected]
[email protected]
 
S

Slawomir Telman

Dear Shamsul,
I use STEP5 (v 6.5) and S5 135U with two CPU type 928B each with EPROM (with coordinator).
The program creates all needed DB for both CPU after Overall Reset (standard data). Warning. If You need actual data You must save all actual DB before You replace EPROM into RAM - for example in STOP mode. You can modify program if RAM module exists into CPU. I use the following way to replace EPROM with RAM for CPU 928B:

1. Switch Coordinator and both CPU to STOP mode.
2. Switch OFF (main power supply) the PLC and replace the EPROM module with RAM module.
3. Switch ON (back main power supply) the PLC
4. First I make Overall Reset, then Reset.
5. Switch CPU into STOP mode.
6. Download program form PG to CPU in the following way:
- transfer DXO,
- transfer DB1 (or all DB if I need actual data for a process)
- transfer PB, FB, .... and OB as last.
I don't use function "transfer all program ".
7. Switch into RUN mode both CPU, then switch into RUN Coordinator.

Regards
Slav
[email protected]
 
G

Gerard Leemkuil

It's very simple to overall reset the PLC.
1) Remove the battery.
2) Switch off the PLC
3) Reset PLC by reset switch
4) Reload new program with programmer. Or when (e)eprom are inside the CPU,
the firmware will reload the program to System Ram of CPU
Try this, it works
 
D

Donald Pittendrigh

Hi All

The 115U's have on board function blocks, the 928B which is a 135U has standard function blocks which you buy on a disk. I would not jump over the
cliff for it, but I am willing to take a side bet without checking first, that the 928B doesn't.

The idea however is quite correct.

Regards
Donald Pittendrigh

> The 928B CPU has some standard Siemens function blocks stored
> in internal ROM. If you download your program to the CPU, these
> blocks are also transferred but because these blocks are already in
> the CPU you will get a message like "Block exist in Eprom,
> continue or abort". Just press continue for every standard function
 
Top