counter output state

[shellie]

I'm generating 2 digital pulse trains on the counter output channels, ctr0 and ctr1, using  DAQmx Create Channel (CO - Pulse Generation - Time).vi. I need to use these signals with my external hardware, but I also need to know the state (high or low) of these pulses within my VI at any time. I have tried to use the property node to give me the counter output state, but seeing as my pulse frequenct is 500Hz, it isn't sufficient. I've attached an example of how I'm trying to do this.

Any suggestions of ways to overcome this? Or is it possible?

Thank you!!!!

[MarkLe]

Hi Shellie,

This method seems to work fine for me if you slow the pulses down greatly (1 second high time and low time), you can see the counter state changing on the graphs fine.

Obviously, it's going to be really difficult to 'see' 500Hz in real-time on your graph (unless you magnify the timebase greatly and just look at small sections of your signal), but if the loop is set to update fast enough, then I think the property node should still be able to represent the states OK.

Remeber that in order to 'see' a signal changing at 500Hz, you need to sample it at at least double that rate (i.e. 1kHz). So in your example you should change the delay in the loop down to 1ms, so that (if at all possible) it 'looks' at the property nodes states 1000 times a second.

What do you need to do with the state you generate with these propety nodes in your vi?

Hope this helps!

Mark Lee

National Instruments

[shellie]

Hi Mark,

Thanks for that! I'm pretty new to Labview, and you really clarified a few things for me.

I'm looking into whether I can demultiplex my signal using LAbview rather that the hardware method, and so need the states from the counter channels to do this. I'm not too sure whether it's going to be possible.

Thanks again,

Shellie