OPC UA HDA - access to data for application needs

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1

Hello,
is it possible to use the memory formula from Help ‘160 + ID + Q’ to access OPC UA HDA data in an application?
Or in general, is there a way to get data from OPC UA HDA to application?
Thank you
Regards
Michal Malek

2

Hello,
As far as I know there is currently no function/function block available in Automation Studio to read out the historical data (AsOpcUac library doesn’t have such a feature).
In Automation Studio, we use the OPC UA Historizing and this records entries only in DRAM. You can use it e.g. with OnlineChartHDA widget in the mapp View visualization.

3

Hello,
I need to display data in a chart while also using it within the application. I see two options:

  1. Use HDA and somehow retrieve the data from DRAM.

  2. Use my own data buffer and load it into a chart.

I used the second approach frequently back in the VC4 days, assuming the chart component can handle data from a ring buffer.

Perhaps my question can be better phrased as:

Which chart graph in the mappView widget catalog supports plotting data from a ring buffer?
Regards
Michal Malek

4

Chart widgets that use array variables are XYChart and LineChart.

You can use LineChart for time series charts and XYChart for charts that deal with the relationship between the two data.

If VC4 is familiar, you can configure a trend page in VC4 and then connect it in the VNCviewer widget. (This will require a license.)

5

Hello,

You’re absolutely right about XYChart and LineChart — I’ve used them several times. However, I need to display data from a ring buffer (I’m fairly certain that HDA uses one).

The VNC viewer widget is an interesting approach, but I need to maintain a strictly uniform theme in my visualization.

Thank you
Regards
Michal Malek