Trends with Memory Tags

I need to make a Realtime Trend with a memory tag. I don´t have date base to save data, so I only have the memory tags. The Easy Chart needs HistoricalTags, so I can´t use it. I don´t know how do it.

In the property editor, make sure the filter (funnel icon with a letter next to it) is set to “All”. Then, find the “Chart Mode” property in the “Behavior” section of the Easy Chart properties. Changing chart mode to “Realtime” will enable it to show realtime data.

1 Like

Thanks! I already did, but I can´t view nothing. The Easy Chart doesn´t draw the tag.

That’s weird. Did you make sure the date and the axis min/max were set to good values? You’ll probably want to bind the end-date to the current time (if you didn’t already)…

There is no simple way to store tag history without a database, and to show a trend you need a history. Have you seen this post:
Might be an easy way to show your trend.

use a litle database, (like mysql, or similar) just the necesary to create all your charts.

It would take a fair amount of work to whip something up (though I feel like its been done a few times before), but conceivably you could use scripting to build up a dataset in memory, and then feed that to a chart (note: the classic chart, which operates on standard datasets, would probably be a better choice).

You could probably create a template like:

  • Internal property per tag, bound to the tag value
  • Property change scripts that look at those properties and then append data to the dataset on a classic chart
  • Some logic to limit it to a certain number of rows or time so you don’t end up running out of client memory.

Good luck.

I you just want to generate a time-series dataset in memory, look at the recorder() function in the Simulation Aids module.

I agree with chi - was also going to recommend looking at the free database module which comes with a free database from @nmudge. Quick video overview(s) and if it works in your environment then you have all you need :grin:

In effect, what this means is that Ignition does not have realtime trending? You can only trend historized data? What is the purpose of the Chart Mode ‘Realtime’? Why does it let you create a realtime trend and drag a tag onto it if it doesn’t work?

Realtime mode on the chart just means it shows a moving window ending now. You can set things up to drag tags onto charts, but you need to store history for the tags before they’ll work. @pturmel’s and @chi’s suggestions above are a couple options.

I have done a script to record a few values in a dataset (and trim it when data gets too old) before as @Colby.Clegg mentions above. It’s not hard to do, and gives a third option that’s easy to use in the classic chart (not EasyChart) if you don’t want to use any third-party modules, Historian, or SQL Connector.

If you don’t want to record to the database, consider the recorder() expression function in Simulation Aids.

1 Like

Hi @pturmel,

I've download your simulation project but i cannot find an example of that recorder function.
Could you maybe show me where to find it.

Is this function also compatible with perspective ?