cWhat communication method should I select for OPC connection?
Question
cWhat communication method should I select for OPC connection?
Answer
When you operate as OPC server
The communication method when the connection from the OPC client is accepted as the OPC server is selected by the OPC client side.As for the OPC server, it corresponds to the following communication methods, and please select it by the OPC client side.
Synchronous communication (cache, device)
Asynchronous communication (cache, device)
Change Notification
When operating as an OPC client <Selecting a communication method>
The "Change Notification" is not a request from the OPC Client, but a notification of the value change from the OPC Server. In "Change Notification", when the cache value is updated by the update cycle, if there is a change in the value, it will be notified to the OPC client.
Compared to this, in "Synchronous Communication", the OPC Server checks the data in the argument of the method for the request from the OPC Client and returns it. During this time, the OPC client waits until the method returns.This will cause the OPC client to wait, so we usually recommend "Change Notification".
However, when a lot of change notifications are generated, the load of the OPC Server side may become high when "Change Notification" is selected (e.g. when the value change is performed at ms intervals, etc.).In such cases, we recommend using "synchronous communication (cached values)"."Synchronous communication (cached value)" will stabilize the load since communication is performed at regular intervals (set by the update rate).If the load of the OPC server is high in the "change notification", please try to communicate by "synchronous communication (cache value)" and check the operation.
*Synchronous communication (cache value)" will reduce the load by going to the cache, so usually choose "Synchronous communication (cache value)" instead of "Synchronous communication (linear value)".