How can I send digital Output at faster rate than 1ms period?

[Júlia]

Hi!

I'm using a PCI-6229 to send digital outputs to a power source and I need to send n different numbers in binary code. I need this to be periodic so I've used a while structure and the diferent numbers as the different components of an array. In this way the while loop writes the "task" repetedly at the period I have set to the loop using "wait until next ms multiple". So, it does what I want. The problem is that I need the loop to work at a higher rate than ms. It would be great if I could make it go at 0.01 ms. I have tried and even when the "wait until next ms multiple" doesn't like doubles it tries to work at this rate but the signal is not 100% periodic and I need it to be much more precise.

Does anyone have an idea to solve my problem?

Thanks a lot,

Júlia

[Dennis_Knutson]

You can't use software timing to achieve a higher rate. It is silly to use the wait until next (or the more proper wait ms) on a Windows os. You have hardware timed digital I/O on that device which is capable of much faster and very precise rates.

[Júlia]

Thanks for the answer!

Excuse me, could you please explain me a little bit more the solution you suggest?

I would be very pleased!

[Dennis_Knutson]

Have you looked at the DAQmx examples? I don't recall the exact names but I would suggest filtering by your hardware. Basically, you create an array of samples that is output by the internal sample clock instead of one sample at a time in a loop. Of you do use a loop, it would be to repeat the entire pattern.

[Júlia]

OK, thanks a lot for the answer. I've been looking at all the examples but I haven't found the precise one. I have been trying to use them but I don't know what do I have to connect , I have no idea about timing... Could anyone help me find an example of high frequency (100kHz) digital output generation? My device is a PCI-6229 controlled through SCB-68.

Thanks a lot,

Júlia

[crossrulz]

I think the example you want to look at is Digital - Continuous Output.vi.  You can just use the onboard clock and set the sample rate to whatever you need (100kHz it looks like).

[Júlia]

Ohhhhh!!!! Thanks!

That example was exactly what I needed. Now I need to do the same but with to channels... I mean, I need to send two different patterns simultaneously.  What do you recommend? Using 2D U32 in write DAQ.vi or... Labview doesn't like it when I use twice the DaQ timing (sample clock).vi... it says ''The specified resource is reserved. The operation could not be completed as specified.'' What is the best solution?

[crossrulz]

You need to create a task that handles both channels.  Then you can use the Multiple Channels, Multiple Samples version of the DAQmx Write.

[Júlia]

Thanks to all of you! My project is now working properly!