Error -200019: ADC Conversion Attempted Before Prior Conversion Was Complete

Updated May 24, 2018

Reported In

Hardware

  • NI-9207
  • Chassis for SCXI

Driver

  • NI-DAQmx

Other

Applies to All NI Hardware with an ADC

Issue Details

  • Why do I get error 200019 when I increase the rate of my DAQmx task?
  • My task will not run because of error 200019
Error -200019: ADC Conversion was attempted before prior conversion was completed

Solution

The following can be possible solutions for error -200019:
  1. Reduce the sampling rate to allow the ADC more time to make the conversion.
  2. Check the specifications for your device and make sure the sampling rate is less than the maximum allowed sample rate.
  3. Increase the timeout value on the DAQmx read.
  4. If you are using an external clock, additional steps can be found here.
  5. If these other steps don't resolve the error, try resetting the NI MAX database. This will remove potential corruption within DAQmx tasks, and the required reboot will force any running tasks to stop.

Additional Information

Error -200019 occurs any time the ADC is requested to convert the analog signal to a digital representation before the current conversion is completed.  The ADC has a conversion rate that the sample clock cannot exceed.

Note: Simultaneous sampling cards will have one maximum sampling rate no matter how many channels are used. Non simultaneously sampled (multiplexed) cards will have a maximum sample rate that is dependent on how many channels are being sampled. For example, an aggregate sample rate of 250 kS/s when acquiring 4 channels of data results in a maximum sample rate of 250/4 = 62.5 kS/s per channel:
 
Simultaneous Sampled Example:

NI 4472 Sampling Specifications

Aggregate Sampled Example:

NI 632X Sampling Specifications

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