Is it possible to obtain the LOAD MEMORY (RAM) as a number on the program to generate an alarm?

Hello alkimux;

To answer your question, I know of no SFB/SFC that returns the size of the used load memory (in bytes or percent)from a S7-400.

On the other hand, why do you want to receive this information dynamically? The load memory does not increase unless you do a download of the CPU program, and generally you do not do that very often once commissioning is over.

Very often in our important projects with a S7-400, we would use a RAM card for commissioning, since downloads are frequent, and switch to a flash EPROM card of adequate size when the client accepted the project. This made a download a little harder to do (and removed the requirement of battery support for the PLC program) and changes to the content of load memory remain stable.

Hope this helps,

Daniel Chartier

Hello alkimux;

If this is a client requirement, you have no choice.

However, you could warn him of the consequences of his requirements, and have him implement a scheduled (monthly?, for example) evaluation of the memory usage from the programming software, and suggest a compression of the load and work memory blocks when it increases above a specific value.

Hope this helps,

Daniel Chartier

Hi alkimux

while I haven't had the need to use this particular combination yet, SFC 51 with SSL-ID W#16#0113 should do the trick (assuming S7-300/400 usage as this is posted in the classic Step 7 conference).

Truth be told, I'd rather keep an eye on the (non expandable) work memory via this and fit a large enough RAM card for the load memory.