Communications between RSView and ControlLogix via OPC

  • Thread starter Cristina Barreto Lopez
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Cristina Barreto Lopez

I need to know which is the best method to optimize the communications between RSView and ControlLogix via OPC. I Have two options: 1. Two topics for one PLC. Each topic with one poll rate and one rate update. 2. One topic with different nodes at different Update Rate. Thanks.
I have been having many problems with this setup!! and Rockwell knows it. I would recommend using PLC5 tags, not arrays like I'm using. Make sure you use a consecutive set of registers. Also setup RSView to scan all tags, but never log them, that way they are always on scan. You will get great scan time by having all tags scanned all the time, better than trying to seperate them out. They will be better optimized that way too, even though you are scanning many more than you need!! 1 topic is what I am using.

James Ingraham

I used two topics, one for each PLC. Using PLC-5 tags (as suggested above) renders the whole point of ControlLogix moot. We do this on a routine basis (often with more than two PLCs) and have no problems with update rates at about 0.5 seconds, even with 5k+ tags, none of which are set up as PLC-5 mapped tags. -James

Mike Johnson

For one job, we used one topic per PLC. That job had 6 PLC-5C and 4 ControlLogix PLCs. Only 2 ControlLogix PLCs are accessible through Ethernet, all of the PLC-5Cs have scheduled ControlNet connections to the ControlLogix processors that have Ethernet connections. However, depending on the data and the importance of the data not all are scheduled. Hence, we have topics that have data sources that are coming from the unscheduled bandwidth of ControlNet then through Ethernet and others are just coming through Ethernet. The data from the unscheduled bandwidth is pretty slow but acceptable. The rest seems to have an update time of about 0.7 seconds for about 4000 tags. There was no PLC-5 mapping except on the ControlLogix to PLC-5C ControlNet connections. I did not see the need to use PLC-5 mapping for OPC communications. With ControlLogix, you will use more memory as compared to a PLC-5. Also, the version of RSLinx does matter as far as OPC is concerned. I think version 2.20 or better works the best for OPC.