Y2 axis for unit conversion

[sraykens]

Unfortunately, I do a lot of work with non-Metric units, but generally take the measurements in Metric.  I'd like to be able to have the Y2 axis display converted units without creating a new channel, adding to the graph, adding a new channel to my graph, modifying the begin/end points so that the new signal perfectly matches the metric version, etc.  

For example, if I had position vs time, and my Y1 data is in meters, I'd like the option to add the Y2 axis in feet from the graph setup.

[AndreasH_Ha]

The functionality you describe is available for 2D axis systems in DIAdem REPORT. If you open the settings for the scaling, you will find a field which allows you to set the unit you want the curve to be scaled to for displaying. The list of units is the one defined by your unit catalog.

Can you please describe what is missing ?

[sraykens]

The feature is ALMOST there...I'll use an example I'm looking at right now to make it easier for me to explain...

I have 4 curves of kPa (on Y1) vs time on X.  If I add Y2 and make it units of psi, the values on Y2 are not equivalent to the units on Y1.  In this case, Y1 is 0-15 kPa and Y2 is 0-2.5 psi.  However, 15 kPa is equivalent to 2.17 psi, so the Y2 scale is incorrect for the curves shown on the graph.  I tried it on a different graph with the same units and Y2 came up as 0-15psi with the same 0-15 kPa Y1 axis, which is obviously far from equivalent.

The method I've used to get around this is to duplicate my curves so that I now have 8 curves.  Then I manually change the highest value on Y2 until the new curves directly overlay the original curves.

Also, I was given these directions from NI Tech Support, which were much more difficult but equally unsuccessful:

1) Make sure that your channel has units associated with it.

2) Create a second channel which has the scaled units. From the analysis tab, select Channel Functions » Convert Channel Unit. Select your original channel in the Channel to be calculated field, and select the units of the scaled channel. (For me, I'm selecting km/h). Make sure you do NOT store the result in the original channel. Select OK to create the new channel.

Most likely, it will be named "UnitConverted".

3) In the Report section, add a new Simple 2D Axis System.

4) Select the time channel, then CTRL-select the speed channel and the unit converted channel. Drag these channels onto the graph.

5) Right click the graph and select Display.

6) Go to the Axis Position tab and add a new axis on the right.

7) Go to the Curve List Tab set the Y-Axis value for the UnitConverted curve to Y2.

😎 Choose one of the curves, and set the color value to No Color.

9) Click OK.

[sraykens]

Also, please see issue 7289193 for another user with the same request (and exact same response received as myself).

Thanks!

[Brad_Turpin]

Hi sraykens,

When I try to reproduce your scenario, I get the correct graphing behavior on the second Y axis (0 - 2.17 psi).  I have a ZIP file containing my fabricated data file and the corresponding TDR file that looks to be working correctly on my computer.  Unfortunately, I don't see how to give that ZIP file to you on this DIAdemIdeas exchange forum.  Neither could I find the Discussion Forum you referenced above.  My email is brad.turpin@ni.com if you're willing to send me an email.  Or I could post the ZIP file to NI's outgoing ftp site...

On a side note, I think this product suggestion is quite valid in that this axis scaling option does NOT exist for VIEW.  Assuming we get your REPORT graph to behave correctly, I'd still see this as a request for similar functionality in VIEW.

Brad Turpin

DIAdem Product Support Engineer

National Instruments

[Walter_Rick]

Thank you for your request.

Since DIAdem 2012 we support an individual unit conversion for each axis in a 2D axis system. Please use the setting of “Curve and Axis Definition”, “Axis Parameters” – “Unit”

Greetings

Walter