Applies To:
  • CitectSCADA
  • CitectHMI

I am using CitectSCADA version 5.50 with a redundant trend server pair. When one server has been down and is restarted I normally see the trend data (and hence the display) update from the other trend server. However, on a few occasions I have noticed that this update seemed to fail. When that happens, the data is never updated to deficient server. 

This issue has been addressed in CitectSCADA version 6. Trend servers now keep track of gaps in Trend data at runtime as well as startup. Gap fill requests are sent to the Redundant Trend Server. These now have timeouts and retries to insure the requests are completed.

The sensitivity of runtime gap filling can be controlled by the the [Trend]Gapfilltime or [Trend]GapFillSamples parameters. If the latter is set to a value greater than the default value of zero, then the number of missed samples is used rather than any gap time value.