How Can I Sample at More Than 2 Hz with My NI 9219?

Updated Dec 12, 2017

Reported In

Hardware

  • NI-9219

Driver

  • NI-DAQmx

Issue Details

I am performing a continuous acquisition with my NI 9219. It seems that regardless of the Sample Rate I select, the device will not go past 2 S/s. How should I configure my device to achieve faster rates?

Solution

The NI 9219 is by default only able to sample at 2 Hz because the ADC Timing Mode setting. The NI 9219 is built with a delta-sigma analog to digital converter with a default High Resolution ADC Timing Mode, which according to the NI 9219 Datasheet (page 9), has a conversion time of 500 ms. You can change this setting so that the module is able to run at faster rates.

If you are using NI MAX or a DAQ Assistant to configure your Virtual Channel or Task, the Configuration tab and then the Device tab, and change the ADC Timing Mode to High Speed. This will allow for a minimum conversion time of 10 ms (100 S/s).
 

If you are configuring the Task programmatically in LabVIEW, you can use a DAQmx Channel Property node to set the ADCTimingMode property to High Speed.
The ADCTimingMode can found in Analog Input » General Properties » Digitizer/ADC » Timing Mode.
 

Additional Information

  • The 10 ms conversion rate is only achievable if no channels if configured for thermocouple input. If one or more channels are configured for thermocouple input, the minimum conversion time in High Speed mode will be 20 ms (50 S/s).
  • The conversion times for the different ADC Timing Modes are as follows:
No channels in TC mode:
High speed10 ms for all channels
Best 60 Hz rejection110 ms for all channels
Best 50 Hz rejection130 ms for all channels
High resolution500 ms for all channels
 
One or more channels in TC mode:
High speed20 ms for all channels
Best 60 Hz rejection120 ms for all channels
Best 50 Hz rejection140 ms for all channels
High resolution510 ms for all channels

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