Graphing Pump on/off data

[andybdjuk]

Hi, i wish to graph Pump On/ Pump Off info on a graph that already I display temperature's on. I would like it to be a solid black bar along the botton of the graph about a cm high representing on/off.

I have attached an example of what i would like to achive

Is this possible in Express and any suggestions

Thanks

Andy

[AzeoTech]

This requires two steps:

1) if Pump On/Off is an output, then its history only gets updated every time it changes state so you have to create another channel to create a history. The best way is to actually read a digital input so you get actual feedback of the current state, but if you can't do that, you can simply create a channel with Device type Test, I/O type DigOut and then in the event of one of your analog input channels put:

PumpGraph = PumpState[0]

The reason you put it in the event of an analog is so you get a value with every analog value. Here I'm assuming PumpGraph is your Test channel and PumpState is your digital output that controls the pump. Of course if pump on/off is an input, you are probably already reading it once a second or so and therefore have a continuous history.

2) next, you need to add a new trace with PumpGraph (or PumpState if its an input). Put it on a right axis and set the axis to plot as a bar graph. You may have to tweak the bar width. Now you have two choices, you can adjust the right axis scaling so the bar appears 1cm high, or you can set the right axis scaling to match the left axis and then add a multiplier to the trace to get it 1cm high. I'd probably do the second as it will be a lot less confusing.