Stagger OPC DA Poll Times
We're trying to coordinate OPC DA polls of a SCADA system to maximize polls while minimizing the impact to the OPC server. Specifically, we have 7 branches in the OPC DA server. We can either break it up into 7 Sessions and 7 DataSets, or 1 session with 7 groups and 1 DataSet (does it matter?). Either way, we'd like the groups or sessions to "take turns". 1 second the first group would poll, the next second the 2nd group would poll, then 3rd group a second later, etc. After group 7 polls, it's group 1's turn again. I know you can set a pol frequency, but can you say specifically when to poll? Thanks!
1 reply
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Hi ,
We don't have a way to stagger the "polling" times, whether you split it across 7 sessions or 7 groups within a session. Perhaps there is something on the OPC server side that could control this.
Not sure if it matters, but technically we're not polling the OPC server. We subscribe to the server and the Update Rate tells the OPC server how frequently we want to receive updates, if there are any. There may be slightly less overhead if you're doing this through one session as opposed to seven, but the difference is probably small.
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