High ControlLogix CPU usage due to Comms

[Glu3]

Hi all
I am having problem with a L75 CPU which running 100 % CPU Usage. It doesn't have any Continuous Task and 50% of the CPU is taking by "Comms" which is very unusual to me. Can you guide me in to which direction I should investigate this?

More information:
- All of the PLC-PLC communication use MSG instruction, there are about 12 instance of MSG, most of them are execute every 500ms (using timer), the reset are of 250ms.

 

[guile_nery]

I don't see any problem there. The CPU will always increase / decrease resources to communications based on its tasks and internal usage. The CPU never idles. If you are having issues one thing I noticed is the amount of memory that is being used versus what is available. To me it seems that this number is close to the point you might be having issues with processor timing-out task or taking longer to resolve logic.

 

[JaxGTO]

If you are using a GSV to monitor external IO they should be on a timer as well and not hot branched. That could account for the 14% which seems high.

 

[Glu3]

I don't see any problem there. The CPU will always increase / decrease resources to communications based on its tasks and internal usage. The CPU never idles. If you are having issues one thing I noticed is the amount of memory that is being used versus what is available. To me it seems that this number is close to the point you might be having issues with processor timing-out task or taking longer to resolve logic.

there is a yellow warning banner like this https://imgur.com/a/SDtZuGg, so I thought it must be an issue
On a different PLC (that is also without continuous task), Comms doesn’t take up the free space and leave it as “Null”