OpcDaCom Questions

[sarclimber]

I am using OpcDaCom as my driver to talk to Red Lion's OPCWorx server.  OPCWorx is currently talking with 2 different Red Lion HMIs in two different remote locations and sending data to my Visual Basic application which displays various data from the Red Lion HMIs.  Should I be using two different instances of OpcDaCom, one for each Red Lion?  I am currently using only one and it is working.  I am getting ready to connect two more Red Lion HMIs and display data from them as well.  My network is not the fastest as it uses multiple mediums and I will need to "wait" a little bit longer for connections to come alive so I am thinking I need to add more instances of OpcDaCom to accomplish this.

If I need to add more instances, where in the OpcDaCom.vb code is the best place to "wait" and give the connection time to be established.  When I tried to connect to a third Red Lion HMI I got a "Failed OPC Subscription Start" which I suspect is due to a slow network speed.

To summarize: use multiple instances of OpcDaCom?  Where in OpcDaCom.vb should I "wait" for a slower connection to be established?

Thx, Chris

[Archie]

In OPCDaCom.vb at line 481 is where it is failing. This is coming from the OPC server. This is directly from the OPC server. There may be a setting somewhere in the server or in the OPCSubscriptionItem(0) object that may allow the timeout to be increased.

[sarclimber]

Changed the Connection and Transaction timeout values in OPCWorx and that seems to be working fine.

Should I be using multiple OPCDaCom drivers in my application, one for each touchscreen, or is one sufficient?  Three touchscreens are up and running now but there is potential to go as high as 20 in the future.

Thx, Chris

[sarclimber]

Checking in again, anyone have an answer for using one or multiple OpcDaCom drivers in my application?  Have 3 touchscreens connected now, will have up to 20.  All communicating through OPCWorx server.  Thanks.

[Archie]

OpcDaCom is merely a wrapper around the OPC Foundation's class library which in turn is an interface to the OPC Server. All of the OpcDaCom instances all funnel through the same server, so I wouldn't expect any performance difference whether you use one instance or multiple.