Historizing Trends Basics

Questions regarding the use of the UaExpert.

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UPC_student
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Joined: 17 Oct 2022, 12:07

Historizing Trends Basics

Post by UPC_student »

Hi!
I'm researching the use of the OPC UA communication protocol between a client and a Universal Robot model. I want to keep the setup as straightforward as possible and I have currently very limited knowledge about OPC UA besides basic configuration. Keep this in mind, please!

I have already an OPC UA server up and running (the robot is the server) and with a local program on the robot I can interact with some OPC variables I have created. The variables can be seen in real time in my PC via UAExpert.

Creating the OPC variables is done in the robot (basically you can set a name, type and value). I want to make a trend with one of the OPC variables (Boolean, True/False). I'm trying to use the History Trend View but I'm encountering an error where the program says: "Added item does not support historizing"

What could be the problem and what would be the easiest way to solve it?

I've tried to change the Historizing attribute in UserWriteMask (which is set to False) but "AccesDenied" and WriteNotSupported" errors show up in the Message Log.

Finally, I want to add that I have been able to plot a trend using another program, OPC Expert. No permission errors showed up there.

Thanks so much in advance.

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Support Team
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Re: Historizing Trends Basics

Post by Support Team »

Hi,

OPC UA has multiple feautres that represent data coming from the server. The live data (variables and values) representing actual process data, the events and alarms representing notifications triggered by conditions, and historical data representing backdated series of data stored in a server.

To indicate that the server has not only actual value, but additionally has some historic values for the particular Node, the server can show with the historizing attribute. Obviously your UA server has not internal storage/database for providing a historic set of values for this node.

Simply spoken, historic data is not supported by your server, you should check with the server vendor, if such feature is planned, and how it can be configured in the server.
Best regards
Unified Automation Support Team

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