6602: delay 3rd pulse train in software?

[ztruth]

Hi

LV7.1

6602 card

How do I make 3 retriggerable / contiuous pulse trains. (adjustable freq and duty cycle )

The 3rd pulse train needs to be delayed in software from 1st train (adjustable .1us to 10us)

???

Thanks

Ryan

[Jarrod_B.]

Hello Ryan,

Thanks for posting to the forums.  To address your question, I am assuming that you want to generate three retriggerable finite pulse trains since it wouldn't make sense to have retriggerable continuous pulse trains (one would run right into the next).  There is a LabVIEW example called Gen Dig Pulse Train-Finite-Retriggerable.vi that demonstrates how to do this.  You could set up three of these tasks using your 6602 (but no more than four since this type of task uses two counters).  In order to get one pulse train to be delayed or offset from the other two, you can use the Inital Delay input to the DAQmx Create Channel VI. 

I hope this helps!  Let me know if you have any questions about what I just described.

Best regards,

[ztruth]

Hi Jarrod

I am also discussing this idea on another 6602 thread; for a continuos pulse train; I do have questions.

1. can I use a software trigger? If not how should i hardware trigger?

2. is there a limit to the number of seperate train outputs? per counters? can you explain?

3. is there a delay resolution limitation?

4. should I use another card for this type of output.

Thanks much

Ryan

[Jarrod_B.]

Hello Ryan,

1.  There are no software "triggers" per se.  You can start the task in software whenever you want.  That is the closest you can get to a software trigger.  For hardware triggering, you could connect a TTL signal to the gate of your counter and configure your task to start on either the rising or falling edge of that signal. 

2.  A finite pulse train generation task requires two counters, one to generate a pulse train of the necessary frequency and duty cycle, and one to gate that signal.  Other pulse generation tasks only require one counter.  So for example, you could have twice as many continuous pulse trains running on a counter board as you could finite pulse trains. 

3.  The resolution of the initial delay is directly related to the timebase that is connected to the source of the counter.  For example, if you are using the 20 MHz timebase as the source, the smallest initial delay you could get would be 2/(20 MHz) or 0.1 us.  For more information on this, please refer to the following KB's:

How Can I Generate Two Pulse Trains Phase Shifted from Each Other on My E Series Card?

What Are Acceptable Values for Initial Delay for a Counter Generated Pulse?

4.  The 6602 will work just fine for the type of application we've been discussing. 

I hope this helps!  Let me know if you have any questions on what I've described.

Best regards,