Error reading counter values from OPC Server using Labview 6.1 and DSC 6.1

[DonTan]

I am trying to read a counter value from the TOP OPC Server (by Software ToolBox) using Labview DSC 6.1 as the OPC client.

I configured an analog tag to monitor the value of the counter using the Configure Tags feature.

At the same time, I created a digital indicator to display the value of the counter on the front panel using the HMI wizard.

However, when I run the VI continuously, the value of the indicator remained at 0 even when the value of the counter has changed.

The range of the counter value is from 0 to 3. The correct counter value was displayed using another OPC client, OPC Quick Client supplied together with the TOP OPC server.

I have boolean indicators on the front
panel which monitor the status of discrete inputs and outputs of the OPC server. These boolean indicators get updated without any problems.

I have tried to change the type of tags to bit array but the digital indicator still display only 0. I have also tried to change the representation to long and byte but the digital indicator value remained 0 when the VI was run continuously.

Please advise on what could be done in order to read in the analog values i.e. counter values from the OPC server.

[Khalid]

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Couple of things to check: check the Update Deadband and IO Group deadband for this counter tag. When you browse the OPC Server (from within the TCE) and create the Item, what's its data type -- Analog? BitArray?

Also, by "when run continuously" do you mean by hitting the run-continous button on the toolbar?

You could also try (for troubleshooting purposes) using the Read Tag VI. Check the Tag status output of this VI for any errors.

Hope this helps.

Regards,

Khalid

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[steven@ni]

Don,

As Khalid mentioned, first check the deadband for the i/o group and also for the tag engine. Make sure that these are small enough that you will see the change. Also, make sure that the scaling is correct for the tag. Remember: the deadbands are %'s of the scaling. So, if the scaling is incorrect, then you may not get the updates as often as you planned.

Also, try reading the tag with a read tag.vi. Lastly, make sure that the front panel connection has a green connection light and that the indicator is in a while loop while you are running the vi.

If all of these things fail, you can try reading the counter value with a different OPC Client to make sure that the server is truly opc compliant. You could use the server explorer 2.4.1 (made by Nati
onal Instruments).

Let me know if these suggestions don't help.