Trigger with a Chassis 9189 and 9401

[Grigori]

Hello everyone,

I have got a chassis 9189 and a digital device NI9401. I am monitoring the signals with a NI9205 device. I have an external device which give a 5V Trigger signal and I want to use this signal to trigger the logging of my sensors which are connected to NI9205. I am reading the signal of my external device with the NI9401 and than I give this signal to the logging. But how I can capture the signal with a high rate, since the NI9401 device is able to capture signals with 100ns?

I attached the acquisition of the digital input. There I can only set a acquisition rate of 10kHz, when I set 100kHz it does not work. When I read the incoming signal, I want to read the signal directly, so I do not want to set the samples per channel in the sample clock.

What do you think? Is this a good approach?

[GerdW]

Hi Grigori,

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@Grigori wrote:

I attached the acquisition of the digital input. There I can only set a acquisition rate of 10kHz, when I set 100kHz it does not work. When I read the incoming signal, I want to read the signal directly, so I do not want to set the samples per channel in the sample clock.

What do you think? Is this a good approach?

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No, it's not a good approach!

• Reading DAQ data "1 sample on demand" is only recommended for <=100Hz.
• Transferring data using local variables easily leads to race conditions…

Suggestion:

Use the "N samples" read mode for DAQmxRead! Usually you read about 1/10 of the samplerate, so at 100kS/s you should read 10k samples…