I have several tester PCs with identical equipment and versions of Labview 7.1. The TAG configuration I am using was provided by the company we purchased the equipment from. One of the testers is having an issue with the DSC module or configuration. If I write an identical analog value to a Tag with a Tag Write, the Tag Read performed for verification returns a value of 0.
Using the Tag Monitor to analyze the problem, I found that immediately following the write command the value of the Tag in the Tag Monitor reads zero. If the value written is different from the previous value, the Tag Monitor will then read the expected value after a minimal delay. If the value written is the same value, the zero will remain. I compared this behavior to the other testers and the Tag Monitor does not show a value of 0 at any point.
I have ruled out a problem with the equipment because we can connect the equipment to another tester PC and there is no problem. At this point, I think the reason the Tag Read returns the 0 is due to the value not being updated because writing the same value would not exceed the deadband. I am now trying to determine why the 0 appears from the Tag Write.
I am using the Industrial Automation OPC Server 5.1.
Any thoughts or ideas about how to remedy this problem would be much appreciated.
Thanks,
-Dave
