Answer question
If cahce update rate of my controller does not alling with OPC client polling rates
I have 800M controller set up with below cache update rates at my OPC server for 800M:
-High :500ms
-Above Normal: 2000ms
-Normal: 5000ms
-Below Normal: 10000ms
-Low:30000ms
OPC Server manual 3BSE035983-510 (pg 26-27) states i need to set my cahce update rate from controllers twice as fast as OPC client polling rate.
For example if an OPC client creates an OPC group with an update rate of 1000 ms. This means that items added to this OPC group will be reported to the OPC client once every second. In the OPC server, the MMS communication for this group is put in the High category, which means that items in this category will be read from the controller every 500 ms (3BSE035983-510 -pg27) .
I have realized our call groups in OPC client (Matrikon OPC Explorer) set to 9 sec as default. I am not sure if it is a right practice. Does it mean the calls related to the polling group will be classified as "Above Normal" instead of Normal and cahche request will be done in each 2sec and causing unnecasy load to controller? Or it will force the OPC server to do a direct call to controllers in each 9 sec?
Should I change the "Normal" cache update rate of controllers to 4500ms or change polling rate of my OPC client to 10 sec for better perfomace?
