Slow OPC Reads and Writes


We’re using the system.opc (system.tag is not an option in our case per IA support) write and read functions in our project and they seem to be taking a lot of time to complete. We’re seeing write times of between 10-20 seconds. I’m not sure if my expectations are too high or if this is normal.

Is there anything I can do with scan classes or other things on the back end that might speed these commands up?

This is using Proface Pro-Server over DCOM.k


How many operations are you trying to do, and how often? What are the nature of the operations? (Like, how many values are you trying to read/write at a time?)

Scan classes wouldn’t come into play here, unless you had other tags defined that were, in fact, using them.

Depending on the operation, the opc server, and the end device, 10-20 seconds could be possible, though generally that is not the case.

If you want to get a bit more advanced, you could go to Console>Levels in the gateway and look for the “COMServer” and “COMSubscription” loggers, and turn them both to “Debug”. Run your system for a little bit, and then export the logs from the Console page and attach them here, or email them to support (referencing this post and my name). That might give me a better idea of what is going on.


Thanks Colby. I think it would take an email to fully explain everything so I’ll try to get some logs to you by the end of the week.