how to measure multiple inputs with a NI 6220 card

[GertW]

Hello,

I'm currently playing with a NI 6220 DAQ card. I've found how to measure one input frequency using a counter but I've got 6 different inputfrequencies which I want to measure and only two counters. I would like to measure my 6 inputs without having to switch from one input signal to another.

How can I do this?

Thanks,

Gert

[Dennis_Knutson]

What's the frequency you need to measure? The analog inputs only have a 250 Ks/s sample rate but if your frequency is no more than 1/2 this, you can acquire an analog signal and use a function like Extract Single Tone to determine the frequency.

[GertW]

its 22kHz I have to measure.

[Dennis_Knutson]

Using the analog inputs for all 6 at once would not work since your effective sample rate would not be high enough. You could sequentially use two separate tasks of 3 channels each or use the two counter inputs and a single analog input task with 4 channels.

[GertW]

I don't want to measure all 6 channels at once. I just want to prevent the use of extra hardware to switch from one channel to another.

What i like to do is connecting all 6 channels to my DAQ card but only measure one channel at a time.

[Dennis_Knutson]

Then just use 6 DAQmx Read tasks or 6 separate DAQ Assistants sequentially.