Acquiring a signal from two separate DAQs at different rates at the same time

[Muneesh]

Hi I am trying to setup a system where I need to build two separate arrays one from two separate sets of data. The data needs to be brought in at the same time, but at a different rate. One set is from the PCI-4472 and will come in at ~10Hz, while the other is from a SCXI-1102 that is connected one channel on a PCI-6070E at ~3-5Hz. I was wondering how to have the two be read at the same time, but at the different speed. I am using LabView 6.1. Thanks in advance.

[chutla]

Hi Muheesh:

Since your DAQ's are working at an exact multiple of one another, what you could do is fill alternate channels with some "DUMMY" data...like zeros. Then you could index the array and match it up with the faster card. It might seem like a waste of memory, but it will give you two sets of aligned data, which seems to be what you need. If you're operating them at some weird multiple, it's a bit trickier. Whatever you do, you're going to have to insert some bits somewhere. Look for a least common factor (LCF) of your sample rates, and see if you can divide by that before logging the data.

Eric

[chutla]

Muheesh:

Here's another trick I hadn't thought of earlier. If you save your data as a WAVEFORM, there is a Waveform operation called ALIGN TIMESTAMPS, which may just do the trick for you. You will have two different column lenghts, but the x values will correspond, which is what I think you're looking for.

Let me know how this works for you

Eric

[Muneesh]

Hi Eric,

This sounds like a great idea. I'm going to give this waveform idea a try. Here's hoping it works. Thanks for your advice!!