on 2011 Oct 25 12:52 PM
Hi community,
we want to use the SAP PCo in our environement, our engineers think that there's probably a problem with using the PCo.
We want to trigger some MII transaction through the PCo by reacting on a single bit provided by the OPC server. I would suggest to use onTrue as TriggerType, but now how is the signal set back to 0 after triggering the MII, do I need to build a PCo Tag Query that sets back the bit in the OPC? Or is it better to set the signal automatically back after a certain time?
There seem to be some doubts about the reliability of the SAP PCo!
Maybe someone out there has a similar use case or a kind of Best Practive for such a scenario?
regards
Markus
Request clarification before answering.
If you want the activity of the MII transaction to reset the trigger bit then you will need to set up a tag query to write a 0 to the bit. If resetting the bit is not dependent on MII transaction activity then it would be better to manage the setting and clearing of the bit in the PLC or control device if possible. You can pass the address of the bit in the Notification message by adding it as a string constant in the Output tab of the Notification, and then MII could assign the address to a tag query template dynamically to handle the write back to the source as part of the transaction you are calling from PCo.
- Steve
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For toggling status bits, I have found the best method to create two seperate notifications for each data point I want to monitor. I have trouble with the onchange reliablity. I have an OnTrue when the value goes to 0, and another OnTrue when the value goes to 1.
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