Clock source for encoder measurement 6624

[tim-t]

I am trying to use a 6624 card to interface to quadrature encoders. In trying to test the interface using DAQ Assistant I have run into an apparent problem. I am using Labview 7.0 and NI-DAQ 7.2. I select DAQ-Assistant->CounterInput->Position->Angular and the DAQ Assistant window appears. I would expect that "Internal Clock" would be available as a choice in the CLOCK_SOURCE pull-down menu. The only choices available on this menu are: PFI(38,34,30,26,22,18,14,10), RTSI(6-0), and PairedCtrInternalOutput.

Is it possible to use the internal clock for decoding position and how can this be accomplished?

Thanks.

[gus]

I assume that you are using "N Samples" or "Continuous" as your Acquisition Mode. In this case, the "Advanced Clock Settings" that you are configuring is the Sample Clock Source. With counters, there is no onboard sample clock, so all sample clocks must be generated externally to the task. That being said, you can use another counter to generate the frequency at which you would like to receive samples of the position measurement task.

For example, if you are measuring position on ctr0, you can use ctr1 to generate a continuous pulse train, using either LV or another assistant task. Then you would select "PairedCtrInternalOutput" as the Clock Source for your position measurement. This scenario has the benefit that it doesn't require external connections in ord
er to connect the sample clock.

Hope this helps!

[josef_slg]

Hello, xan you specify this regarding the pci6602 counter timer card. I am using at the moment 6 counter for encoder measurement, and I want to incrase the sampling frequency of my card, how ?
How do I apply the continuous pulse train to my clock source
Thank you very much.

[MickeyD]

Hi,

Thanks for using the NI discussion forumns.  I see that your issue is also posted at this link.

6602 as X4 encoder/external clock

I am going to go ahead and look at that post since there seems to have been some discussion there.

Have a great day,

Michael D
Applications Engineering
National Instruments