How do I use a lookup table in LabVIEW SignalExpress?

[fish8100]

I have a USB-6008 DAQ and would like to take readings from the analog input, pass those readings through a simple lookup table to obtain new values that are to be used to program analog output values in the USB-6008.  I know how to do something like this in C, but I'm not sure where to start in the LabVIEW SignalExpress world.  Can this even be done with SignalExpress or is LabVIEW required?  It's a very low budget project so I would prefer to use SignalExpress LE (free) if possible.  I don't mind digging for all the implementation details- but would like a pointer on where to start and which software is the least expensive way to go.  Many thanks for any help offered.

[NIthan]

Hello fish8100,

I'm don't think SignalExpress has any explicit lookup table functionality, but there is plenty of math and formula functionality. From what I understand, you want to input a signal, and then based on that input, output a signal that has some relation to that input. If you can convert the lookup table into a formula, then you can make a task similar to what is shown in the attached picture. Is this what you are trying to do? Let me know if this helps or if I misunderstood the question. Thanks!

-Nathan H

[fish8100]

Hi Nathan,

Thanks for your response.  I don't have a formula, only a set of points that are entered and then interpolation occurs between them.  I loaded an eval copy of LabVIEW and found Express>Arithmetic & Comparison>Scaling & Mapping which has an interpolation function defined by a table of entered values.  Is there anyway to do that with SignalExpress?  I don't think the purchase of a LabVIEW license will be possible for this project.

Anyway, thanks again for the help.

FiSH

[NIthan]

Hello fish8100,

I've been playing around in SignalExpress today and I can't seem to find a way to do this using a table. This is more of a programming functionality which SignalExpress lacks (Use LabVIEW for programming, not SignalExpress).

All of the ways to process a signal are going to be under "Add Step»Processing" and there doesn't seem to be a way to use any of the processing functions to reference a lookup table. I'm sorry I can't be more help, but it looks like this functionality is simply not available in SignalExpress.

-Nathan H 

[Seth_B.]

One possible option you might consider is a Custom Scale that you create in Measurement & Automation Explorer, then use for your Analog Input task in SignalExpress.  You can create a "table" style scale that will do what you are describing I believe.

If you need the unscaled data as well as the scaled data, you can create two virtual channels (one to read scaled and one to read unscaled).  This will decrease your sampling rate, but will give you both scaled and unscaled data.