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RE: Problem with settling time in DAQmx Assistant

Good day.

 

I am a postgraduate student at the University of Pretoria. We are using a PCI 6229 ADC, SCXI 1001 chassis, SCXI 1102C amplifier and SCXI 1303 terminal block for experimental measurements. We want to take thermocouple measurements at high sampling frequencies but at the moment we cannot log data at more than 500 Hz before the MAX warns of possible inaccuracies due to problems with the settling time. MAX recommends reducing the sampling rate to address this issue.

 

However, it seems strange to be limited to 500 Hz sampling rate considering that all the aforementioned hardware specifies much greater sampling capabilities; less than half of the SCXI 1001 chassis ports are currently in use. I would like to know whether there are any software and/or background processes inhibiting the obtainable sampling rate? Also, is there any way to work around the settling time problem of the amplifiers to increase the sampling rate that can be accurately achieved?

 

All help will be greatly appreciated.

 

Thank you.

 

Regards,

 

TUKS_student

 

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Hello TUKS,

 

Are you currently using a Thermocouple task? Does this problem occur if you were to just get raw voltage from those channels? This may be a limitation of the task in software itself, thermocouple measurements are meant to be slow since temperature does not change quickly. If you want to go faster you may have to acquire raw voltage along with the voltage from the cold junction channel and calculate temperature by hand. I would like to note that if you were to sample faster that you would have a considerable amount of data that does not change much at all, is there a reason why you have to go so fast?

 

Regards,

 

-Travis E

National Instruments
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