USB-6212 counter resolution

[jacyhs]

I would like to maximize resolution at low frequency (<500Hz).

Documentation indicates 100Khz clock is available, yet when I simulate, the options are 20 & 80 Mhz. I believe I can use the “Frequency Out”, which can be divided by 16, as an external clock source for the counter(s). Can the counters be cascaded, that is, use the output of one counter as a clock source for the next counter.

While simulating, what property node would I use to get the actual frequency generated?

Thanks, Jeff

[dansch]

Hi Jeff,

You are correct that only the 20 and 80 MHz clocks will show up initially, but you can still specify the 100 kHz Timebase as well. To do this, you will need to right-click on the control/constant for the input terminal and select I/O Name Filtering. A small dialog box will appear and you will need to check "Include Advanced Terminals". You should now be able to select the 100 kHz Timebase. Additionally, you should be able to type in "/Dev1/100khzTimebase" and it should work as well.

As far as your other questions, you can use another counter (such as ctr1) as a source for your input counter (such as ctr0). You will have to setup the counter (ctr1) as a pulse train generation task and run it, and specify the source of your input counter (ctr0) to be "/Dev1/Ctr1InternalOutput". This is another "advanced" terminal that can be accessed when changing the I/O name filtering. The same applies for using the frequency generator, except that you would specify the source of ctr0 to be "/Dev1/FrequencyOutput".

Regarding your final question, when performing a counter output task, you can find the actual frequency being generated by placing down a DAQmx Channel Property Node. The specific property to read would be the "CO.Pulse.Freq" property and can be found under Counter Output » Pulse » Frequency » Frequency. Hope this helps,