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G'day all,

I would like to know a couple of things. Firstly I have set up a Trend graph on an HMI screen on a V570 OPLC. I have set up four different curves and the trendand it all seems to be working good. What I would like to know is where does the data for the trend get stored on the OPLC. Also how do you clear the old data.


The Sparky

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The Trend history can be saved on the PLC RAM memory - Press right click on the trend in the system tree and you can decide how many samples you wish to save in history.Then you can view this history by pressing on the 'M' button you have on the Trend variable.

Please note that the history trend which is saved in the PLC RAM memory erased after power cycle.

You can use SD card for saving the trends and then view the trend on the PLC HMI or even on your PC.

There is an example in VisiLogic --> Examples --> Project Examples --> SD --> V570_SD_Card_Trend_Read_Write_Append.vlp

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  • MVP 2014

Just a further note, so the trend data is stored in a "closed" format, you can't access it as general data from within the ladder. It can only be accessed via the trend HMI object or by saving to SD card.

If you also want to see and manipulate the data from inside the ladder, it is not a big deal to add a Data Table as well. So you run the trend and the write to the data table simultaneously, logging the same data to both. Of course with the data table you can also log additional data that you may not wish to include in the trend.

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  • 4 years later...
  • MVP 2023
9 hours ago, Declan Byrne said:

On the V570  how long back do the trends save? Eg months days?

According to the Help file, you can hold up to 32,000 samples in history *TOTAL* for all trends in the PLC, so it's a function of sampling rate and how many trends you're monitoring.

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