Multiple Signal Acquisition

[jaredg00]

I need to write what I am certain is a fairly simple VI but am having some problems.  I will have two analog signals that I will need to acquire at the same sampling rate (possibly as high as 5khz) and then write the data to a file.  I can either have the data in two files or in one, but regardless of the form will need to be able to compare data points between the two waves that were acquired at the same instant.

The VI that I have currently written will read and write data from one wave, then read and write from the second, and then repeat, such that it is not possible to compare values from the signals for corresponding moments in time.  Does anyone have any suggestions on how to write the VI I need or a link to a sample VI that performs the tasks I need?

Thanks.

[EdDickens]

This is going to depend on several factors, so you really to supply a bit more information.

What version of LabVIEW are you using.
Is it an NI DAQ card?
If so, what version of NI-DAQ and are you using DAQmx, and Express VI or Traditional DAQ.
If not, what is it?

In general, a single acquisition VI can scan multiple channels at a time, you just need to set it up correctly. Usually you just need specify multiple channels in the configuration, but this varies depending on the above conditions.

Ed

[devchander]

You will find such programs in example Vi's shipped with labview.

if u still have a doubt, post your VI on this groups and we will be able to answer u better

regards

Dev

[jaredg00]

Thanks for your response Ed.

We are using a NI DAQ card, BNC-2110.  I am not sure if we are using DAQmx, Express VI, or Traditional DAQ, but would assume we have whichever is more common.  The version of labVIEW that we are using is version 6.1.

Any tips on how to set it up to record multiple input channels at the same time with these specs? 

[Dennis_Knutson]

The BNC-2110 is not a DAQ board. That's an accessory that connects to the actual DAQ board. Since you're using 6.1, that means you're using traditional DAQ. DAQmx is only available for 7.0 and higher. To do multi-channel acquisition, all you have to do is add the additional channels. I'm assuming that you have an AI Config. For channels 0 and 1, just enter 0:1 into the channels control. Then you can use a single read and get both channels at the same time.

[EdDickens]

What Dennis suggested is correct (as usual)

Since it looks like you are using NI hardware, you could look in the Examples and find something that's close to what you want to do and use it as a starting point. Just be sure to save it with a different name so you have to use again later.

If you don't know how to get to the Examples, look in the Help menu and select "Find Examples". A dialog will open where you can browse for different examples. Double click on "Hardware Input and Output>DAQ>Analog Input>General" and you'll see several examples to choose from. Look for one called "Cont Acq&Chart (easy immed).vi" I think this might be close to what you are trying to do.

Let us know if you still need help or if you have it from here.

Ed