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UniLogic Trends Capability?


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I'm looking to implement a trends graph on the HMI screen with particular user capabilities. I'd like to be able let the user select the timescale on which to view the data (by minute, hour, day, week, etc). What are ways to implement this?


From what I can tell, the simplest way would be to have different data samplers for the same variable that logs data at different time increments. But obviously this would be memory intensive. Is there a more efficient solution?



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  • 2 weeks later...

I agree that the ability to change trend time scales is relay required with other option that I already raised here. I hope this will be implemented soon! meanwhile this is my walk-around;


I don't think you need several different Data Samplers for that. You can just copy the trend object once defined on several screens, and then just change the X-Axis Time Frame for each screen.i guess this is also memory consuming, but for sure less that several Data Samples + several trend objects.

If you wand to change the sampling interval dynamically, change the Data Sampler BI interval to 00:00:00 and use the "Data Sampler.Force Sample" bit in your ladder.


Hope it helps.


Other issue that need to be fix is that Data-Sampler is "forgetting"  the defined file name after boot or reset, and then continue with a new default file name based on Time/Date stamp. This question to Unitronics: Is that issue already on the wish list?



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If the Data Sampler is marked as retain, a compiling warning excepted:


"System Struct Tags Retained "Data Sampler1". You have marked Tags within System/Automatically Created structs as Retain. This is not recommended, since it may cause unexpected results"


please advise.



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  • 3 weeks later...


I have a problem that might be related to this topic. Suddenly (after a Power Off/Reset) all my trends have stopped. When I open the trend it empty and the Run/stop button displays Run.

If I press the Run button nothing happens. I am still able to open and view the History trends.

Also all my trends have status -3; Save file error (File name may contain illegal character), but my file names are the same as when the trends was working.

In my Project I use 12 data samplers/trends, 4-8 variables in each trend, sampling interval 1s - 1min. Can it be that the SD card is full? Do I have to delete history to avoid running out of memory, or is this automaticcaly handeled by Unilogic?

My SDcard is 16GB


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Hello again.

Refer my previous post on this topic. After I changed my SD card to a new empty one, the trends are working again. So I assume that the problem was related to running out of memory.

What can I do to avoid this from happening again? Where can i se how much memory is laft on the SD card? Should history files be deleter from the ladder program, or are they deleted automatically when the card is full?


Anders Meeg

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