How do I mark a "not measurable" event on a chart history?

[Kejoglo]

I have an application which is working very well and takes measurements - continuously plotting a result on a chart. The chart history is typically a 100 or so measurements. I plot on the chart both an upper and lower tolerance limit, hence the measurment plot should hopefully stay between the two (straight lines) limits.

Occasionally a sample is "missing" and when this happens a "measurement" of zero is given. This is currently displayed on the chart as a sudden drop to zero. The users like this as it shows them clearly that the sample was missing. All OK so far, however...

On rare occasions a sample is present and is measured but for reasons I will not go into we know (and the software can determine) that the measurement result is actually invalid. This situation I call "not measurable" in that although a sample is present it actually cannot be properly measured. The question is this; how do I show this on my chart history?The chart history plot is by far the most looked at display of data for the users. I realise that I could show a message box saying "not measurable" (and intend to do so) but this would only last for that measurement cycle. How do I "mark" the chart to show that there was a sample but that it was not measurable.

I don't particularly want to use a zero value because that is being used quite nicely for the "no sample" situation. Also I don't want to simply not plot anything because the fact that the sample was "not measurable" is potentially very important indeed. Ideally what I would like is to put a marker, say a thick vertical line at the position where the invalid measurment is, in order to both block it out to show that it is wrong and also show there actually was a sample there in the first place.

Any ideas as to how I can do this? Sorry this is a bit wordy!

Regards

Kevin

[GerdW]

Hello Kevin,

just put a second line of data into your chart. This 2nd line is kind of boolean: 0=sample ok, 1=not measured. Configure this plot to show as steps instead of lines and adapt the values 0/1 to your sample data to span the full range. This way you get vertical bars in the background of your sample data...

[Kejoglo]

Thanks,

I'll try that or something smiliar in any case.

Regards

Kevin

[Henrik_Volkers]

I like Gerds solution (could be three 'lines' with different  colors for "missing", "not measurable", "OUT OF RANGE" )

Another way: a (SGL or DBL) value of NaN (Not a Number, you can get it as a constant ) will not be shown on the chart.

[TimM(AE)]

Hi

I have come up with a quick fix for using a chart which might give you a few ideas. This is just a quick fix and isn’t very nice at all. The green dots are meant to represent the immeasurable data, I have just triggered them by a set of limits. You would be better of using an XY plot and an array which you constantly up date. Using an XY graph will give you a lot more options such as using cursors to mark certain points.

I have attached my quick fix and an example of using text on an XY graph

Hope this at least gives you some ideas

Tim

AE NI UK and Ireland