How to acquire data from 2 chs of the same DAQ card at different sampling rate

[Tushar_Jambhekar]

I am using single DAQ card (either 6013 or 6014) in my system i want to acquire data from 2 (or more) channels with following requirements

1. sampling rate of each channel should be independant of each other (say one is 20 Hz and other is 15 kHz)

2. data from all the channels should be acquired simultaneously.

3. coding must be done using DAQmx VIs

I have tried out following things

1. I created separate task for each channel: i found out that two tasks can not run simultaneously even though the channels are different

2. I tried out single task with two channels included in it. and i used 'channels to Read' property to determine from which ch. i want to acquire data: this method works fine if the sampling rates are same. but if i change the sampling rate of one channel it gets reflected in other channels as well.

can somebody help me out to solve this problem.

i will appreciate if somebody can post the sample code as my deadline is approaching

[Dennis_Knutson]

The DAQ board has a single conversion clock so you can't really set different sample rates. Under certain conditions, you can do this. Otherwise, you're going to have to sample at the highest rate. Please also note that the boards you're using do not have true simultaneous acquisition. with a single A/D, the channels are muxed so that you will have a very small delay between a sample taken on one channel and a sample taken on the next.

[Tushar_Jambhekar]

Hi Dennis Knutson

Thanks for your suggestion.