how do I scale arrays of waveforms?

[oilyfingers]

Hi, I hope you can help with this.

I'm reading in 6 channels of analog data  from a USB 6008 at 1000 samples/second, in 1000 sample blocks  in a  loop . The data arrives from DAQMX as an array of 6  waveforms.

I want to (y-)scale all the data such  that channels 0, 1, 2 are divided by 3 (because the electronics has a 3x gain  op-amp on those channels) and channels 3, 4, 5 are divided by 15 (because the  electronics has a 3x gain, and there is a 5ohm resistor and I'm trying to  measure current).

You'd think it would be ridiculously easy ....  but :
(1) labview's 'scale and offset' vi only works on  individual waveforms (not arrays of waveforms)
(2) inserting a matlab or matscript node doesn't allow me  to work on waveforms, only arrays
(3) using a simple 'divide' VI it proves impossible to set  the denominator as just a single  number .. '3'!

any ideas? as usual it's the kind of problem people must  face all the time

Dave

[smercurio_fc]

Use an array of values rather than a single number:

[Hillman · Accepted solution]

Hi Dave,

This is how I would do it - use array of divider values.

Hope this helps - example in lv 8.6.

Kind Regards,

[DeltaVUzay]

Well, what about scaling with different constants and adding different constants of array like Ax+B to all channels.

This would help much for me.

Best Regards,

Bertan

[GerdW]

Hi Norian,

nothing has been changed since the solution to this question was posted 10 years ago!

Use constant arrays to calc your scaling…

(Or even apply scales on your DAQmx channels!)

[DeltaVUzay]

But still getting an error like below. How can I solve this?

Best Regards,

Bertan

[GerdW]

Hi Bertan,

why do you need a FOR loop? Why do you create a 2D array of waveforms?

Why do you work with 2D arrays? (Use IndexArray instead of ArraySubset!)

It's all your fault… 😄

[crossrulz]

---

@DeltaVUzay wrote:

But still getting an error like below. How can I solve this

---

I would use the DAQmx scales so I wouldn't have to worry about doing the math on my own.

But with your setup, you really should wire your 2D array straight to the FOR loop, autoindexing on it.  This will iterate over the row.  Now you just use Index Array to get the two elements in your row and multiply by the first, add the second.

[DeltaVUzay]

Thanks for your brief replies!