Boolean values from modicon OPC UA PLC are logged in historian core strangely

[aaronrsturm]

Howdy,

Boolean values in my historian are not being recorded as true or false, instead the tag history just counts up or down forever, I see the same behavior with a memory tag or a OPC tag from my PLC.

I am using ignition maker edition 8.3 and historian core, so I don’t know if this is the normal behavior of historised boolean values, but I was expecting them to just be recorded a 0 or 1. Here is an example power trend of 2 boolean values (heat is currently on, cool is off).

And the associated tag configuration:

[andrew.budaiev]

Do they come as Booleans in the Tag Browser?

[aaronrsturm]

Yes, If I browse and add tags directly from the OPC server they are automatically added as booleans.

[Matrix_Engineering]

Welcome!

Some further insight for you:

I’m trying to understand the recommended best practices for configuring Ignition Tag History, specifically how the following pieces are intended to work together:

• Tag Group (normal execution rate) • Historical Tag Group (e.g. Default Historical) • Sample Mode (Tag Group vs On Change vs Periodic) • Deadband Style (Auto vs Analog vs Discrete) I understand that the Tag Group controls how often the tag is evaluated/read, while the Historical Tag Group controls how often the historian evaluates whether a sample should be stored. However, it’s not entirely clear when it is best to reuse existing tag groups versus creating a dedicated Historical Tag Group,…

[aaronrsturm]

That’s an interesting read! I did already set all my boolean tags to discrete style deadband that are set to “on change” recording. I might also change my process variable to discrete now, to get the more predicatable behavior.

Here are some more examples of trends for my same boolean tag:

[Matrix_Engineering]

I don’t know if you can use Embr Charts on Maker, but if you can, then you should.

[aaronrsturm]

@Matrix_Engineering

Embr Charts

I was able to import the Embr Charts module, looks like it’s free for anyone to use!

[aaronrsturm]

All,

I was able to fix this manually by changing the pen setup in my powerchart for boolean tags, specifically setting aggregateMode = "LastValue".

since I didn’t want to do do that everytime I added a new tag I applied this on change scipt to the props.pens attribute:

def valueChanged(self, previousValue, currentValue, origin, missedEvents):
    # Iterate through all pens currently on the chart
    pens = self.props.pens
    
    for i in range(len(pens)):
        try:
            # 1. Get the Source Path safely
            # Structure based on your JSON: pen -> data -> source
            pen_data = pens[i].get("data", {})
            source_path = pen_data.get("source", "")
            
            # 2. Check if valid tag path
            if source_path and "tag:" in str(source_path):
                tag_path = str(source_path).split("tag:")[-1]
                
                # 3. Check Tag Type
                configs = system.tag.getConfiguration(tag_path, False)
                
                # 4. Apply Logic for Boolean Tags
                if configs and str(configs[0].get("dataType")) == "Boolean":
                    
                    # Fix Interpolation: 'display' -> 'interpolation' = 'curveStep'
                    if pens[i].display.interpolation != "curveStep":
                        self.props.pens[i].display.interpolation = "curveStep"
                        
                    # Fix Aggregation: 'data' -> 'aggregateMode' = 'LastValue'
                    if pens[i].data.aggregateMode != "LastValue":
                        self.props.pens[i].data.aggregateMode = "LastValue"

        except Exception as e:
            # Ignores initialization errors (e.g. when a pen is created but not yet populated)
            pass