clock sample question

Hi ppl,

I have a question for you.

I have a very similar to the attached picture circuit. also you can find here (http://zone.ni.com/devzone/cda/tut/p/id/3615#toc4 , fig.2) I write some data on analog channels out and then I collect the data in the time loop. I don't understand what exactly is happening when I write the data in the buffer. Let's say I have a table of 2D 2-lines and 62500 columns that I want to write in the output analog channel, then read in the analog channel. I do not understand the meaning of the sample clock. (I read on operations 2 devices simultaneously and blah blah blah). What should be the sample clock frequency in the August channel and the channel of the ain and the number of samples per channel in the ain daqmx channel when I want to collect data? (http://zone.ni.com/devzone/cda/tut/p/id/2835; reading the data in example labview). My problem is that I do not understand what is happening when I load the August channel with data buffer; for example I put the sampling clock rate: 1000; meaning he will write each s 1000 samples of 62500 samples until the end of the samples; all of these samples that I drove from my out channel voltage piezo-beam-scanning engines. which means that each s piezo motors will get 1000 samples of tensions? now, I want to measure. should number of samples in the playback channel I put? I put my daqmx reading in the while loop. Let's say I put 100 Samper useful/channel. so, each itteration in while loop it will read the 1000 samples/channel buffer. How will I know that the buffer is already full with 1000 samples when ain channel tries to read?

The process is therefore more; correct me please if I'm wrong. The sample clock will define us the buffer data rate. For example, I load the 2D matrix: 62500 2rows columns; It will load in the buffer and then there are these samples at the August channel of the rate defined in the clock sample string? Then I want to read from the channel of the ain. What sampling clock frequency should I set for the channel of the ain? If the sample clock rate for the playback channel sets the buffer? for example (I put it there 1000 samples/s; meaning it can read 1000 samples per second?) then what the number of samples should be in the read daqmx channel in the while loop?

Please clarify me this point, I'm confused...

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Hi dimani4,

There is a very comprehensive document that answers your questions. You can find this document here.

This article explains the operation of the sample clock frequency and the DAQmx Read reading samples. Quoting the article: "On the hardware side, the Schedule VI DAQmx determines the flow rate of the device/sensor data at the hardware buffer on the data acquisition card.". Here is the 'Timing VI' the sample clock.  Then he also explained that "on the software side, the reading VI DAQmx determines the transfer of the data of the buffer material in the software". "." It is making reference to the samples to read the reading VI DAQmx.

I hope this information specific to your questions.

Tags: NI Hardware

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