Applies To:
  • CitectSCADA 5.50 Service Pack B, 5.50 Service Pack C, 6.xx, 7.00
  • CitectHMI 5.50 Service Pack B, 5.50 Service Pack C, 6.xx, 7.00
Summary:
This can occur if you are currently viewing a trend page in real-time mode (i.e. the trend graph is updating in real-time). What can happen is that if you zoom in on an area of the trend graph, the display will remain in real-time mode (instead of switching to historical mode) and thus the display will move to the current value (RHS edge).  

Solution:
This behaviour can be caused by certain sequences of calls to Trn* Cicode functions. For example, if you do this:

TrnSetTime(some time in the past);
TrnSetSpan(some span);

whilst in real-time mode, the TrnSetTime() call will not successfully change the display mode to historical, due to TrnSetSpan() cancelling all the current requests for data from the trend server. To fix this, make sure you always call TrnSetTime() last in any sequence of Trn* calls.

To work around this problem in the above versions, make the following change to the function _TrendZoomTime() in Include\zoom.ci:

Move the call to:

TrnSetSpan(hDestAn, (nEndTime - nStartTime));

to be situated immediately before the line:

IF (TrnSetTime(hAn, -1, nEndTime) = 274) THEN

And then recompile.

WARNING: If you change the Include project we recommend that you take a backup of your changes as reinstalling or upgrading will overwrite your changes to the Include project.

The above change been implemented in v7.00.

 
Keywords:
zoom jump display pen disappear move  

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