Siemens S7-300 slow response time

Hi all,

We have a setup using 7.9.10 connecting to a Siemens 317fpn/dp on the PLC:s internal ethernet interface.
The PLC is configured to use 50% of the cpu for communication and the PLC scan cycle time is still below 10ms. So not much load on the PLC because of the plc program.

Twice a day almost on a daily basis we get slow response reading tags in ignition.
The issue remains for about 30 minutes and then it goes back to normal.

Bad response:

Normal response:

Any ideas?

Do you have some form of automatic PLC backup system that runs regularly? I would expect PLC programmer operations to create this sort of conflict. The open protocol Ignition uses has lower priority than programmer actions.

No, nothing else connects to the PLC.

Is there a way to log “Mean response time” or “Load factor”.
It would be great for troubleshooting, pinpoint the hours when the error occurs.