Applies To:
  • CitectSCADA 7.00, 7.10
  • Vijeo Citect 7.00, 7.10
  • PowerLogic SCADA 7.10
Summary:

When calling the TagSubscribe Cicode function to subscribe to a Variable Tag, you can pass in the name of a Cicode function as a Callback function. This Callback function will be executed on the initial TagSubscribe call, as well as any time the value of that tag changes.

However, when calling the TagSubscribe Cicode function to subscribe to a Variable Tag which has already been subscribed to by a previous TagSubscribe call, the initial Callback for this 2nd subscription will not be executed.

Solution:
This is a known issue with the TagSubscribe Cicode function which will be fixed in version 7.20. The callback function should be executed on every TagSubscribe call, regardless of whether it has been previously subscribed to or not.

If you are calling the TagSubscribe Cicode function twice for the same tag to add a second Callback for when the tag value changes, we recommend that you either combine the 2 Callback functions into 1 and call TagSubscribe once, or use the SubscriptionAddCallback Cicode function to add the second Callback.
Keywords:
TagSubscribe, Callback, SubscriptionAddCallback

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