Using calibration data within LabVIEW

[michaelj53]

Hi,

Very new to LabVIEW.  I have a VI created by a colleague who is not avaialbe to help for a while.  Resistances from thermistors come out of the DAQ Assistant and are split then fed into an array, then sent to an XY Graph to create a plot of resistance for each thermistor. 

I have a calbiration equaiton (quadratic, with coefficients a,b and c known) that will convert the resistance to temperature and I would like to perform that operation so that the XY Graph shows temperature instead of resistance.

How do I input this conversion into LabVIEW?

Do I have to do this conversion on each signal individually before it goes into the array or can I perform this conversion on the data once as it is sent to the Build XY Graph Express VI? 

I appreciate any help I can get.

Thanks,

Mike

[camerond]

I would suggest you start with a couple of tutorials on LabVIEW that are listed in my sig. (No, I didn't write them.) Then try to figure out what your colleague did.

Getting to know LV first will save you a lot of time and effort compared to having us step you through things, with all the delays involved.

Cameron

[michaelj53]

Thank you, this was useful and I think I've got a good start on doing this.  I'm creating a sub-VI that will do the arithmetic calculation.  One bit of information I've not found yet.  The resistance are held in an array.  I would like my sub-VI to take the data in the array as an input, perform the calculation, then put it back into another array.  How do I tell the sub-VI to read a specific array element and do the arithmetic?

Thanks again for any help.

Michael

[LV_Pro]

If you just want to perform the math on each element and then put them back in the same order there are two possibilites (actually, probably a lot more than two!). The brute force method is to have your calculation inside a FOR loop. When you wire your array to the edge of the FOR loop it will default to autoindex, meaning that each element of the array will be worked on individually. If you wire the result of your calculations to the other side of the FOR loop it will automagically create an array of the same size, and same order, as the input array.

The other one that comes to mind is that many LabVIEW functions will perform their action directly on arrays, so if you are multiplying each array element by a factor, just wiring the array into one input of a multiply, the factor into the other, will do the same thing.