S5 928B out of memory

G

Thread Starter

Glen Boston

I have a Siemens S5 928B with 64K RAM module (I think that is the biggest available). I have been adding a lot of analog signals and now it says there is not enough memory in PLC. Compression doesn’t help. Is there a way to see how much memory is being used for the different memory types? Is there a way to shift some of the reserved memory area from the DB to the P area? Am I going to need to add another processor? Hope some of you S5 guru’s out there can shed some light on this for me.

Glen
 
M

MagicNexus.com

Hi..

Using, from the start, stl instead of ladder (or other) representation will cut down on memory usage (switch to stl and remove the thousands of unused interpreture thingies).Another idea is to have the processor create dbs when needed. Also using indirect addressing when possible..

Have fun!!!

Joseph

STL
Siemens, The Programmers PLC...
 
I do not agree that using STL will make much difference to your program size.

In the PLC menu on the programming package there is an option to show memory details and by making any type of cross reference you will see the relative memory sizes of the different types of blocks in the memory.

Common problem with 136u's is the excessive use of DB's, rmember all the flags and S flags are there and occupy the same memory size whether you use them or not, so use them up and avoid using DB,s unless you need to store permanent parameters which retain status after A plc restart.

Regards
Donald P
 
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Piotr Kowalski

Hello, Glen!

You can solve your problem in two ways:

1. You can configure PLC to load DBs to second memory bank, by default they go to the first one and because FBs, PBs and OBs can be loaded only to the first one, there is no room for them, even if you have some free RAM in bank 2. In manual you'll find which bit to set to do it.

2. That's what I usually do: I divide upload to PLC into following steps:
A. Compress memory.
B. Upload OBs, PBs, FBs
C. Check how much free memory left.
D. Select some FBs or PBs to fill up the memory completly and upload them to PLC again.
E. Upload your DBs to PLC (because whole bank 1 memory is occupied now, PLC will store them in bank 2).
F. Compress RAM in PLC - you'll have some free memory.
G. Always remeber to compress memory after uploading minor changes to PLC (e.g. when you change and transfer on PB or FB).

Regards
Piotr Kowalski
P.S. Excuse me if I my explanation is not too clear, I have to polish my english, still.
 
G
Thanks for the info guys. I'm still not clear how to view actual memory usage. If I look at system parameters, I see hex numbers for different areas. I don't understand what these numbers mean. It looks like is just shows where the memory is located, not how much is being used in that area. I must be missing something obvious.

Glen
 
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Piotr Kowalski

Menu "AG / AG Speicherausbau". It will show you the memory size and the end address of occupied memory. Subtract them and you'll have the free memory size.

Regards
Piotr Kowalski
 
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