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cDAQ speed improvement

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Hello,

 

This is my first post at the forum and maybe someone can help me.

I am switching some output-pins on a cDAQ based system with USB connection to my PC

Just switching on 1 output take about 35 ms but compared to the speed of the USB-interface this seems to be very long. I am using a cDAQ system which has a USB 2.0 interface which has a transfer-rate of 480 Mbps.

Can somebody explain why this should take so long and if there are possibilities to improve this?

I have attached my test-program.

 

Best regards,

 

Wamor

 

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Message 1 of 7
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Try adding a Start Task outside of your loop. Auto-starting the task is going to take a while. For what it's worth, this code gives me an "elapsed time" of between 0 and 1 running on simulated hardware.

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Message 2 of 7
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Hello BertMcMahan,

 

Thank you for your quick response. I tried your suggestions but without luck.

Still I have a delay of about 30 ms. Running on simulated hardware also gives me an "elapsed time" of about 0 or 1.

Running the program on a Digital output-port on cDAQ hardware I got a delay of about 30 ms.

With regards to the USB 2.0 speed this is a lot of "overhead time".

Any idea how this can be improved?

 

Regards,

 

Wamor

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Message 3 of 7
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Look in the Find Examples >>> Hardware IO >>> DAQmx >>> DO

 

For a "continuous" example.

 

Not all hardware can do that so it may be a limit of your hardware.

 

Ben

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Message 4 of 7
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What device are you using? I just tried with a USB-6218 and got a delay of 1ms.

 

mcduff

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Message 5 of 7
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Hello mcduff,

 

Thank for replying.

I am using a cDAQ-9178 chassis with a NI-9375 I/O-card.

 

Regards,

 

Wamor

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Message 6 of 7
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Hi Ben,

 

Thanks for replying.

I will have a look to the suggested examples.

 

Regards,

 

Wamor

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Message 7 of 7
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