Asynchronous Communication

• Set in Central Configuration by setting the UseAsynchronousOPCCommunication to TRUE
• Most OPC applications use asynchronous communication by default.
• The Asynchronous communication mode is considered faster and producing less load on the system.
• By default, Asynchronous communication should be used and only changed to Synchronous for specific reasons.

 Synchronous Communication

• Set in Central Configuration by setting the UseAsynchronousOPCCommunication to FALSE
• Due to backwards compatibility SYNCHRONOUS is the default communication method set by MI on install. It is recommended to change this flag to ASYNCH after install.
• Apriso 9.5 and higher offers an ability to allow MI to read from the OPC Cache for performance. This is done by setting the UseOPCCacheInSynchronousCommunication parameter. Using cache is preferred way of reading data synchronously.

 Recommendations:

• Use Asynchronous by default, make sure this is turned on after MI install (both server and client).
• Test the performance of the OPC server as early on as possible to ensure performance is ok using Asynchronous.
• If required to switch to synchronous – ensure the UseOPCCacheInSynchronousCommunication flag is set to true for optimal performance.