Hi,
Can someone explain to me the following?
I’m using the CP0484 PLC, which has 2GB of memory available.
If I go to Physical view → PLC → configuration → pv memory, I can configure 4GB of PVs.
How does the PLC handle this?
I always raise the values slightly if they fall out their range, but I’m not sure if this is the right way?
shouldn’t this be limited to 2GB and why do I have to modify this myself?
thanks in advance
Hello,
the X20CP0484 has various memory types onboard.
2 GB Flash
256 MB DRAM
64 KB FRAM (non-volatile)
The volatile variables share the DRAM with all modules loaded from the flash, e.g., the operating system, driver, or application.
I would initially keep the default value for the variable memory. If it’s not enough, you can always increase it.
Regards
Stephan
Hi Stephan,
Thank you for your reply.
what i still don’t understand is that i can configure 4gb but only have 2 available.
Hello,
If you can type it in, it will simply mean that the automation studio hast no limit for this configuration in its .hw File.
Some Values are only checked while executing on the Automation Runtime and will lead to errors there.
The PVs are all present in the RAM of the PLC. Also the Automation Runtime will need a part of the RAM. (256 MB)
You can use the SDM or the Online->Info to check how much RAM is used on your plc.
I am also not sure why exactly we have this setting , but it is sometimes good that you get remembered that memory isn’t endless and you can overthink how you have managed your data. So i am not agains having it.
If your Application is Running on the PLC you obviusly did not exxeded the available memory. But Automation Runtime can’t create Memory where no Memory is available. I had lots of cases were i get Logger entrys due to limited resources. They will for sure be triggered if something is not enought.
Greetings
Michael
