Applies To:
  • CitectSCADA 5.xx, 5.42, 5.42A, 5.50, 5.50A, 5.50B, 5.50C
  • CitectHMI 5.xx, 5.42, 5.42A, 5.50, 5.50A, 5.50B, 5.50C
Summary:
We recently installed the [Trend]Rangecheck=2 parameter to allow trending of values outside of the range defined in variable.dbf. This worked but we are now finding that the trend continues to plot values (flat line) in a #COM condition. What we need to do is to plot values inside of the range but show N/A when there is #COM. 

Solution:
This problem will appear if you have got [Trend]Rangecheck=2 or 0

Citect has confirmed this to be a problem in CitectHMI/SCADA version 5.XX . This problem has been fixed in version 6.

The workaround in the mean time is to place Tagread(TagName)<>"" into the trigger field of the trend. Doing this will also do an additional tagread for every point in the trend system which may impact the performance. It is therefore recommended to bench test this solution before implementing.

 
Keywords:
RangeCheck, N/A, flat line  

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