cDAQ and NI 9234: sampling data at a given frequency

[motoDrizzt]

In short: I need to sample the voltage input of an NI-9234 hosted inside a cDAQ-9174, and I need to sample it at 20 Hz. That is, I expect to get exactly 20 samples every second, no one more and no one less. And, as far as I've been able to test, it seems impossible: even using the NI examples there is no way to get data at a given frequency, I always get data at absurdly and totally arbitraries high speed, usually in the range of 1600 sample per seconds. Why is the damn thing ignoring the settings? After a bit it even crash 'cause the software (NI examples) cannot keep the pace with the sample data rate...which is obvious, considering that the hardware is doing anything but what it is been asked to do.

How can I get a few thousand Euros of hardware to do what it's been bought for, before I start banging the head in the wall?? 😄

[pzanini]

Hi motoDrizzt,

Could you try to open the "Voltage - Continuous Input.vi" example attached on this post and try to set it up like it is done on the  screenshot, and post the result that you get?

Just in case, if it does not works, I wuold suggest you to download and install the latest version of the DAQmx driver, that is responsible of managing this kind of instruments communication.
http://www.ni.com/download/ni-daqmx-16.0/6120/en/

Have a nice day!

[motoDrizzt]

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pzanini ha scritto:

Hi motoDrizzt,

Could you try to open the "Voltage - Continuous Input.vi" example attached on this post and try to set it up like it is done on the  screenshot, and post the result that you get?

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Hi pzanini,

my bad, I explained myself poorly. And maybe I choose the wrong forum, too 😄

I'm using plain C# talking directly with the cDaq drivers.