external clock

[barak]

Hi,

when Using the Cont Acq&Graph Voltage-Ext Clk.vi i have Rate and Samples to read controls.

Is that means that evry time my external clock rise (for example) the Acq is done by a sorce clock inside the daq card

at the sample rate value is what Rate controller have?

[PBear]

Barak,

When using an external clock, LabVIEW asks for those two parameters as data points for setting up a properly sized data buffer. You should set your rate to the maximum value that you would expect from your external clock. For example, if you're external clock varies from 34Hz to 40kHz you would set it for 40kHz but the acquisition will be done at your external clock frequency. The DAQ board will be using your external clock exclusively and will NOT be using an internal clock. The 'samples to read' will tell LabVIEW how many samples to pull from the buffer each time the DAQmx Read function is called (every while loop iteration). If that many samples are not present, the DAQmx Read will wait until that many samples are present. If you want the function to read all available samples, wire in a '-1.'


Patrick Barrett

[barak]

Thanks very much,

It realy nice to hear from some of ni supporter.

I have another qustion that i try to understand for few days and it's "killing me"

please help,

I'm using 6133 card, Labview 8.2 and daqmx 8.3

I use the example for using counter0 as pulse train retriger to sample continusly signal.

The problem is that not for all scan rates i use i get a correct respond.

I read in the documantation that the freq of the timer is 100Khz or 20Mhz,What thats meen?

Can i use ant scan rate as i want (10Khz,20Khz,30Khz......).for 10Khz i get good result( the accurate number of samples i want) but for 30Khz for example i get strange results.

I assume that there is some kind of divider in the card that divide the base freq(100Khz/20Mhz), but i didn't found anything

in the documentation.

please help!

[ryan_d]

Hi everyone,

Please keep any discussion regarding the above 6133 question to this thread.