Digital Output using NI 9375 and cDAQ-9174 combination

[ShawnLi2024]

Hello, 

I am trying to use the NI 9375 for a control output of 0- 24V. 
Currently have an issue if using software timed output, the while loop only gives me 20Hz. 
where I need at least 1 kHz to progress. 
From the spec seems like both units can push way more than what I required. 
If I am using hardware timing, I can push more than 1k, but the graph is not able to meet a 50% duty cycle. 

I am using the above simple code. 
Thanks for the support. 

[altenbach]

Your loop has no timing at all.

What do you mean by "graph"?

Where is the terminal of the stop local variable?

Is this running on a PC or a Realtime system?

Yes, you need to do hardware timing.

[ShawnLi2024]

Hello, Thanks for the reply.
Sorry for the confusion. 
I am new to LabVIEW. 

Want to find out what the ideal solution is 
I am not using any timing in the loop because any timing I add will slow down my output speed. 
This loop gives me only 20 Hz max. I am using an external Oscilloscope to monitor the DO channel. 
And is running on a PC. 

What I want the program to do is the following. 

The program I am in does not seem to reach the speed. 

Thanks. 

[GerdW]

Hi Shawn,

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@ShawnLi2024 wrote:

Want to find out what the ideal solution is 

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Please define "ideal"! This might mean different things for you and for us…

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@ShawnLi2024 wrote:

I am not using any timing in the loop because any timing I add will slow down my output speed.

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You were recommended to use "hardware timing". This does NOT mean to add some wait functions in the loop!

DAQmx allows to offload the timing to the hardware, which uses a more accurate clock than your PC can provide…

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@ShawnLi2024 wrote:

I am new to LabVIEW. 

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LabVIEW and DAQmx come with a huge library of example VIs.

Open the example finder and look for suitable examples on DAQmx counter output…

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@ShawnLi2024 wrote:

What I want the program to do is the following. 

The program I am in does not seem to reach the speed. 

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When outputting just one sample after the other without hardware timing then you will NEVER reach that 1kS/s sample rate…

Learn from the examples and use hardware timing!

[ZYOng]

See shipping examples at Help >> Find Examples.. >> Hardware Input and Output >> DAQmx >> Digital Output >> Digital - Continuous Output.vi

Instead of using a shift register to invert the value, use Digital Pattern Generator (Ramp) VI and write multiple samples with a single DAQmx Write VI.