9239 24 bit read rate

[rthalman]

I have set up a 9239 24-bit ADC attached to a cDAQ-9172 chassis.  I then operate the module using the DAQ Assistant.  In the settings for the module (the dialogue that opens when you place the DAQ Assistant vi) there is a setting for the rate of the read out if I want to do continuous samples or N Samples.  No matter what read rate I put in the settings it still reads at 25kHz, which then leads to buffer problems if I want to read a few samples each time or various combinations of the read rate and number of samples to read.  Anyone know why this happens or how to fix it?  I don't have this problem with either the 16 or 12 bit modules and can't seem to figure out what is going on with it.

I am running 8.5.1 on Windows XP.

Thank you,

Ryan Thalman

University of Colorado, Boulder

[ManLongAtNI]

Hello Ryan,

The data rate for the 9239 must remain within the appropriate data rate range. Refer to the Specifications section for more information about the data rate range. When using the internal master timebase of 12.8 MHz, the result is data rates of 50 kS/s, 25 kS/s, 16.67 kS/s,and so on down to 1.613 kS/s. When using an external timebase with a frequency other than 12.8 MHz, the NI 9229/9239 has a different set of data rates.

Regards,

Glenn

Applications Engineer

National Instruments