CPU 315-2DP memory compress...

Hello there, i have a problem with downloading user program to CPU, because of full load memory('bout 88%). I 've tried to compress it, but it has no effect. Is there any solution to erase only load memory, or do i need new mmc card? In CPU is one with 64Kb...
Thanx for any reply.

Hello metaller;
Look at the following description by Siemens of the memory concept of the S7-300 compact CPUs. If your only problem is load memory, expanding the size of the memory card eill do the trick. But if your oproblem is that your program exceeds work memoy, there is no expansion available. You would need to buy a larger capacity CPU.
To see how muck load and work memory is used by your program, open your project folder in Step 7 (offline), right-click on the Blocks folder, and look for the system information tab for the blocks. You will see what the program requires in terms of number of blocks, load memory and work memory; from this you can deduce what you next action could be.
Hope this helps,
Daniel Chartier

Hello there …
Don’t trust too much in my opinion but as far as I know when you compress the memory what you actually are doing is to erase old objects which you reload already. Supposedly in the new SIEMENS PLC, this process is automatic, although not always is working … anyway, if you did it manually and it is not compressing, it means you are actually using all this load memory …then it means that if you try to load some object bigger that 7kb (100-88)%, you are not going to have enough memory.
I shouldn’t say that, but using VIPA what is the same than SIEMENS ( I have my doubts) I had a problem compressing, then I did a reset of the PLC, I reload the hardware configuration and it was working again … although not always is possible to do a total Reset.
A mmc128k use to be around 10-20$ more expensive than 64k …

Good luck.

I might stand corrected on this, but

when I have had problems loading programs beforewith S7-300's, as in modifing programs, I have had to go online with the CPU in stop mode, delete blocks that I will be overwriting such as FC's and FB's this is to allow OB's to remain even in the stop Cpu state, As far as I'm aware the CPU retains the OB's during loading in case there is a problem with the new loaded OB then if ok will write over the current OB to this avail it requires twice the space of the OB's just at that moment in time then you can reload you new FCs / FBs as they will just overwrite their particular device name.,

ps only works if memory required is close to max.....

Cheers

Mylo

pps backup before trying

Thanx guys, but the question was, is it posible to erase it or not? The answer is, as you write, no. I have another MMC card with 512Kb, which will solve my problem, i jast want to know, if other reason is'nt possible...
But anyway, thanx...

If you just want to erase the MMC, it is possible. You go online with the PLC, select all the FC, FB, DB, etc. and then delete. (You can do this from the STEP manager.) Then you can download your project. But this will only be helpful if you have blocks on the MMC you no longer use.