are convert strain gauge reading vi output units in percent?

[Eric_EKOS]

I'm using the "Convert Strain Gauge Reading" VI, and have a question that I could not answer from the help file. Are the "units of strain" output from the VI in percent strain? For example, if my peak strain value output from the VI is 0.35, does this mean 0.35% (i.e., = 0.0035 = 3500 microstrain)? Or is it actually 0.35 (350000 microstrain, which is huge). Maybe this is an obvious answer, but I'm just looking for a sanity check since I can't find this documented. 

[Trevor-B]

HI Eric,

The short answer to your question is that they are in units of strain, i.e. 0.35 (350000 microstrain).

If you take a closer look at the bottom of the help doc, it shows the formulas that are implemented in the VI: http://zone.ni.com/reference/en-XX/help/371361J-01/lvinstio/conv_strain_read/

if you take a look at the formula for Full bridge I for example, you can see exactly what the VI does, and that there is no scaling. You can also open up the VI itself and look at the block diagram, and see that it is actually just a formula node with those equations implemented.

[Eric_EKOS]

Hi Trevor

Thanks for the reply! Looking closer at the equations, that makes sense, and it is appropriately documented. I think my problem was that I was trying to justify my expected strain being off by a power of 100. But now that I think about it, I am powering the strain gauge with a Vishay amp, which includes a gain of 100. If I'm not mistaken, I should be dividing my signal by 100 to get the correct strain value. Does that sound right to you?

Eric

[Trevor-B]

Hi Eric,

That sounds correct! It sounds like you have a good handle on how the VI works.

[Eric_EKOS]

Thanks Trevor. I appreciate the help.