Error -200279:Instance:0:480001, DAQ Assistant doesn't change sampling rate when on continuous for pressure bridge transducers

[graduatestudent]

Hi,

My program buffers after a few seconds. I lowered the sampling rate to 10 Hz, but when I read the excel measurement file I can tell that the time step is too fast, close to 1 ms for each value. How can I slow down my sampling rate?

I am new to lab view and I am trying to write voltages from 7 pressure transducers that output mV to excel for calibration. I am using (2) NI 9237 pressure bridges on a cDAQ NI 9174 chassis. I have the chassis connected to a 25 ft active USB extension.  I do not think the extension USB is the problem because it works fine for the NI 9923 block and NI 9213. Also, when I only read one of the NI 9237 blocks I have the same error. Any suggestions?

[RavensFan]

Read page 8 of http://www.ni.com/pdf/manuals/374186a_02.pdf

The largest clock divisor you can use is 31.  Follow the equation and the slowest rate you can get is 1612 Hz.  In the neighborhood of that 1 msec interval you are seeing.

If that is too fast, then you can use averaging or decimation to reduce the effective sample rate.

Yeah.  You set for 1 sample at 10Hz, but that will be coerced to 1612 Hz.  So try reading 161 samples at 1612 Hz and average them together.  You get the -200279 error because reading 1 sample at a time can't keep up with how fast the buffer is being filled.