What is the highest frequency that the NI9472 can operate?

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Hi

I was just wondering what is the highest frequency that the NI9427 can operate?  At the moment I am operating a digital output using the daq assistance to a on\off sequence with no delay using a vi. I have it connected to an oscilloscope and is reregistering it as 55Hz.  According to the data sheet the I/O delay time is 100µs.

Thanks

[AdamB]

Hi there,

The method you are using at the moment is software timing.  I imagine that the software you have written is dictating the fastest speed at which the device can run (The device will only change it's output when the code tells it too)

In your case I would firstly try using the lower lever digital output functions (DAQmx API) to try and speed up your output.  There are many examples for you to try in the LabVIEW example finder that may be of use to you.

For example: "Write Dig Chan.vi" will show you how to output data on a number of lines.  You can manipulate this example to output a constantly changing pulse train by using a shift register and a "NOT" boolean function call each itteration.

You will find that you can vastly increase the speed of output.  What rates are you aiming for?

I hope this helps.  If you have any more questions then please just post back on this forum.

Thanks

AdamB

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Hi Adam

Thanks for your reply. I wrote a small program using the DAQmx in a stacked sequence loop with two iterations. In the first one a true statements was sent to the DAQmx write and in the second a false is sent with no time delay (I have attached the program). Testing this I got the same result with the frequency being approx 53Hz.  I was hoping to get at least approx 200Hz. If possible you might be able to edit my program if it’s that what is restricting the speed.

Thanks

[AdamB]

Hi,

Try this?

AdamB

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Adam

Thanks for that. With that program the digital out is switching less than 2ms and getting a frequency of over 500Hz.  The only other thing that I am having trouble is with two digial outputs where one has to tun on before the other (Sequence is Digi 1 ON, Digi 2 ON, Digi 1 OFF, Digi 2 OFF).  Is it possibe to do this while keeping the high frequency operation.

Thanks

[GrahamG]

I have had a look at you program. To control multiple lines within the same channel you just need to wire in a Boolean array of whatever sequence you desire to the data input of you DAQmx write VI.

As an example I have written an amendment to the above code to control two digital lines in the pattern defined above.

Hope this can be of some help as an example for you.

Best regards

Graham

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Thanks Lads that program works perfect. Thanks for all the help