Zenon Trending Graph

[shaun]

Hi, does anyone know why this will happen in a trending for total power consumption. Historian was set to 1 min for it and it was normal before and being abnormal at certain period of time as shown in pictures. This is only one variable and I'm no sure why there were many lines up and down. Does anyone experience this before?
Besides, what is that meant for a warning message like this---" Archive 1 cannot be read completely, please set a shorter time period"? Is the recording time too short or the trending display time period too short? How to avoid this kind of warning mesj? Thanks

[markclemens]

Hi Shaun,

Re. 1) It`s hard to tell just based on the screenshots and without a scale for the trend graph. One explanation could be that the total power consumption value received from the IED / RTU / PLC is "0" for a brief period of time, before returning to a regular value.

When you`ve configured the "scan" function in the extended trend screen, you can use this function to see the individual values recorded in the historian for this variable as you move the scanning cursor. This also includes the variable status. A zero value with a status other than SPONT could indicate a communication issue or an issue with the value in the originating device. Alternatively you can use the archive revision screen in the runtime to view the raw data in the historian for the same variable and time period, which also includes the variable status.

Re. 2) This message may appear if the runtime attempts to load data from a historian and exceeds a certain memory usage threshold. Typically this can happen when a very large time span is selected or when the historian is configured to capture spontaneous value changes. In the end however, it boils down to a less than ideal historian configuration.


Best regards,
Mark