FactoryTalk SE Derived Tags

I am summing some variables across several CLX PLCs to display at SCADA. The problem is on a comms failure of a single PLC results in a wireframe on tag at SCADA. This is not desirable since this could occur for maintenance etc.

I am now using derived tags to sum some variables across several CLX PLCs to display on SCADA.

This corrects the problem somewhat but now on loss instead of wireframing the derived tag does not update.

Example PLC1 TestTag=20 PLC2 TestTag=20

DerivedTag=40. If I pull the comms on PLC2 I would expect the DerivedTag=20 but it remains at 40.

Anyone have any suggestions?

Please note I have a lot of macros running and if possible would like to avoid going down this road.

Best bet, would be, as usual, resort to VBA.
Query each individual tag directly in VBA, so that you can determine if there is a failure on one (or more), then deal with that one appropriately (Use last value, drop it, flag as in error, etc).

Derived Tags Mass Edits

I know this is an old topic to post, but the titled is the most appropriate.

Is there a way to edit the Derived Tags in bulk? We wanted to use the derived tags to make an indication if equipment is out of service (several tags could put it out of service, and we want to use the common tag for alarm suppression)

The derived tags are stored as a DTS file which cannot be opened in notepad. From my Googling, it looks like this might be some kind of SQL file, but I'm not sure. Is there a way to export this to excel and then import it back so we can edit 1000 at a time?

Please help.

In Studio, Open the derived tag file. In the editor, highlight the grid. Then in the menu, select copy. You can now paste it into Excel. Do your edits, then paste them back.