Unable to get multiple samples per channel with 1122 and 1322 accessory

[JasonEde]

On labview 7.1 using the DAQ.mx to sample thermocouple readings on a 1122 on a SCXI 1000 chassis, I've been unable to get the unit to take multiple samples per channel. It seems to only want to take 1 sample, move to next channel, take a sample and so on. On the older versions of labview I managed to have it sample say 1000 samples on a channel, move to next channel, take 1000 samples and move on to next channel.... etc...

I've spent a large amount of today trying to get it to work on labview 7.1... I'm unable to find a way to get it to do that with this device. Is it possible?

[devchander]

Is your SCXI Module connected to a DAQ card in multiplexed mode?

When a SCXI module is multiplexed to a DAQ card and you select sampling rate as 1000 samples per second,It works like that.

It scans all the SCXI channels in the scan list one after other, and repeats this cycle 1000 times in a second.

Effectively, you will have 1000 samples per channel in the scan list.

For more suggestions, attach your Code, so that we can see if you have got it right.

regards,

Dev

[JasonEde]

I've attached the test code I've been using. Yes the 1122 is in multiplex mode, but I can't seem to find how to change that.

As I said before I managed this in labview 5 & 6 by just reading the data a channel at a time. I'm sure there must be a way of doing this in 7.1

[devchander]

Just did 2 small changes

1. Converted sampling rate constant to a  control and selected it as 1000 samples /sec, set number of scans to read per channel also as 1000

2. Transposed and connected teh 2D data read by DAQmx read to the chart

Just see how it works

Regards

Dev

[devchander]

Herez the attachment

[pvm]

Hi,

I have the same problem! NI Engineers acknowledged this as a bug in NI-DAQmx. It will be solved in the next version they promissed me.

Eric