Siemens CPU's compatibility

juanmdx · Aug 1, 2007

Hi everyone,

I have a Siemens CPU 928, but it ran out of memory and I got a Siemens CPU 948. I've been searching on the Siemens site, but I can't find the characteristics of them.
What I want is to know if the two CPU's are compatible, so that I can only download the data of the 928 on the 948, or if I need to do some modifications on it.

Juan

curlyandshemp · Aug 1, 2007

juanmdx said:
Hi everyone,

I have a Siemens CPU 928, but it ran out of memory and I got a Siemens CPU 948. I've been searching on the Siemens site, but I can't find the characteristics of them.
What I want is to know if the two CPU's are compatible, so that I can only download the data of the 928 on the 948, or if I need to do some modifications on it.

Juan

This is an S5-135u platform if memory serves me correctly. I cannot recall if the 135u CPUs had an DB1 reserved as the configuration block. If so, that may be the only issue, the 948 CPU may not like the DB1 configured for the 928

Ian

juanmdx · Aug 1, 2007

And how can I check if the DB1 is reserved on the 928?

curlyandshemp · Aug 1, 2007

juanmdx said:
And how can I check if the DB1 is reserved on the 928?

If you have a copy of the program, see if DB1 is present'

JesperMP · Aug 1, 2007

Maybe you should read this FAQ called "Replacing the CPU 928B with 948".

curlyandshemp · Aug 1, 2007

JesperMP said:
Maybe you should read this FAQ called "Replacing the CPU 928B with 948".

Reading that document, the B series of 135u CPUs had DX0, whereas the 115/95u family had DB1 as the configuration block

juanmdx · Aug 1, 2007

So, I've to make a few modifications to my 928 program to run correctly on the 948

gregoryg · Aug 1, 2007

Main difference that may cause problems with repalcement CPU928 by CPU948 is different list of special OB's included in operating system of CPU. Especially: OB180, OB181, OB190..193; non existient in CPU948. If they are used in software you will have to rewite some parts of software. Additionally if there are PID blocks made with FB102 (R64 controller) or Modular PID for S5, you may expect more serious problems.

gregoryg · Aug 1, 2007

As addition to previous post.
CPU928 and 928B have additional RAM memmory called DB-RAM (about 46kB). You can move almost all DB and DX blocks from user RAM to DB-RAM using special OB's or even create them in startup OB's in DB-RAM if they are not required for storing non-retentive values.

Siemens CPU's compatibility

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