Panelview error 634

Hi all,
A customer has an existing Panelview 600 that has apparently operated for some time without fault but has recently started locking out with "error 634 ‘Read Timeout IP:10.50.190.150, Path 1 0; TagV3_String[10.Data,0]".

The same message is always reported and occurs daily. My question is : should I be investigating communication issues or could the string tag cause such an error? The current Interscan Delay for the Panelview is 200ms. The software associated with the tag appears quite complicated

Model# and firmware of the PV?
What PLC & firmware?

I would start with communication issues.
Does it happen every time the screen is opened? Do you ever get valid string data?
Did something change with the PLC program or the networking?
Updated firmware, new periodic/motion tasks, deleted tag, extra computers/devices reading data from the controller?

If the tag gives you valid data sometimes, then look at the network & controller usage. Might just be overloaded with too many requests.