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vanecuci

UDFB local tags dont change state

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I have a problem with the local tags in my UDFB. They don't change their state. For example, when I try to set a coil that has a local tag, the local tag's value remains unchanged (zero). I am using the latest version of unilogic. What can I be doing wrong?   Thanks in advance.

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You have not done anything wrong, when a tag is set for a local property it exists only within that subroutine and the tags are not retained and cannot be viewed. Only global tags have the ability to be retained and viewed. When an operand is set as a local tag it will decrease processing time required by the CPU within a specific subroutine but it only exists for that scan. Local tags are used for temporary memory when the CPU is processing information but discarded as soon as the scan leaves the subroutine/UDFB.

 

You can select the tag within UniLogic and convert it back to a global tag for viewing and troubleshooting in online mode. Once the application is complete then you can modify any necessary tags back to local to decrease scan time.

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