Help on using Siemens S5 IP242A counter card with FB183

Hi everybody,

I try to understand an S5 program exists in an old machine. In this machine we have 2 IP242A counter card used for reading encoders. Refer to Siemens documentaries in the PLC program we should use FB178 and FB179 for programming of IP242A but in this system it uses FB183 for programming tasks. FB183 is the standard Siemens function block that use for IP242B (another counter module card). I try to simulate the system in other location but the system generates the error code 8 in the parameter F-NR of FB183 means "Module identifier is incorrect". I would be grateful if anybody can help me to find the reason.
Also how can I obtain Siemens standard function blocks? Is it possible to change inside a standard function block?

Best regards,
B.Najafabadipour

You would have to contact your siemens supplier or siemens themselves with regard to getting standard FB's for S5.

No you cannot modify a standard block, Siemens protect them and you cannot have access.

In many cases modification of S5 standard blocks (not included in CPU firmware) is possible. Their protection is based on limitations of Step5, like: jumps to other segments, jumps over BE instructins, illegal (too big) segment lengths. But you need very good knowledge of S5 instruction set, block header structures and software that does not check these limitations. For example Step5 for Windows from IBH Softec allows you to use commands resticted to FB blocks in PB blocks.

FB183 is not for IP242A!

Dear Friends,
Thank you for your kind replies but actually I don't know why and how the program in the PLC use FB183, the standard function block of IP242B for programming of IP242A!
The siemens documentation for IP242A based on FB178 and FB179.
but when in other simulation system I use FB183 with IP242A it generates the error "Module identifier is incorrect".
Any idea about the situation and the module identifier error will be appreciated.
Best regards,
B.Najafabadipour

It could possibly be a hardware compatability issue, what CPU are you using on your 'simulation system'?

I believe the IP242A/B were only compatible on 115U systems with CPU part numbers from 6ES5 94-7UB..

...and that the IP242A was not compatible with any versions of the CPU 945

AFAIK there are no similar restrictions if you're using a 135U or 155U....

The original system uses a S5-115U CPU 945 and I use same CPU in the simulator. Actually first I try to use CPU942 but it generates the error code B in F-NR. Siemens documentary say this error means "CPU identification or firmware is incorrect in PLC-S5 135U". I decide to change the simulation CPU to 945 and error code changes to 8 means "module identifier is incorrect".
Are you sure that IP242A can't use with CPU 945?
Is it possible to replace IP242A firmware (EPROM) with IP242B?!
Many thanks before fore your help.

krk said:

It could possibly be a hardware compatability issue, what CPU are you using on your 'simulation system'?

I believe the IP242A/B were only compatible on 115U systems with CPU part numbers from 6ES5 94-7UB..

...and that the IP242A was not compatible with any versions of the CPU 945

AFAIK there are no similar restrictions if you're using a 135U or 155U....

Click to expand...

najafabadi said:

Are you sure that IP242A can't use with CPU 945?
Is it possible to replace IP242A firmware (EPROM) with IP242B?!

Click to expand...

Here's a clip from catalog ST 50 - 1998:

Dear KRK

Thank you very much for your help.
It seems they change the firmware of IP242A to work same as IP242B.
Is it really possible?!!!
After your guidance I also saw it in the CPU 945 catalog's that refer to possibility of using IP242B only.

Best regards,
B.Najafabadipour

najafabadi said:

It seems they change the firmware of IP242A to work same as IP242B.
Is it really possible?!!!

Click to expand...

It certainly looks like it, I presume the 'Upgrade kit' shown in the catalog does just that...