Applies To:
  • CitectSCADA 3.00
Summary:
Question: I have event, periodic and periodic-event trends in my system. When I want to display trends I sometimes get "Cannot mix trends" hardware alarm. Does this mean that I cannot display different type of trends on the same trend display ? Or, is there a way to display them mixed?  

Solution:
Because the periodic trends are time based and event trends are not we cannot display event and periodic trends on the same trend display. On the other hand, periodic-event trends show the occurrence of an event in time, in other words, they are time based. The way they display trends is very similar to that of periodic trends. They scroll in time until an event occurs which in turn is displayed as a spike. Because the periodic-event and periodic trends are time based trends they can be mixed on the same display.

If we summarise

Trend type Periodic Periodic-event Event
Periodic OK OK Not mix
Periodic-event OK OK Not mix
Event Not mix Not mix OK
 
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