Error -200621 When Generating Output Signal Using DAQmx

Updated Feb 26, 2025

Reported In

Hardware

  • NI-9262
  • USB-6251
  • NI-9401

Software

  • LabVIEW

Driver

  • NI-DAQmx

Issue Details

I want to continuously output a signal to the analog output of our measurement card using DAQmx.
The output breaks down randomly after some minutes, (ranging from 1 to 40 minutes) and I get the error code -200621:

Onboard device memory underflow. Because of system and/or bus-bandwidth limitations, the driver could not write data to the device fast enough to keep up with the device output rate. Reduce your sample rate. If your data transfer method is interrupts, try using DMA or USB Bulk. You can also reduce the number of programs your computer is executing concurrently.

Solution

This error occurs when the driver could not write data to the device fast enough to keep up with the device output rate.
In order to resolve this issue, you can add a DAQmx Property Node: [DAQmx Channel, AO.UseOnlyOnBrdMem], after the DAQmx Timing.vi.
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To create the DAQmx Property Node, follow the steps below:

  1. In LabVIEW 2020 and onward, you can add this property node by placing a DAQmx Task from the DAQmx Palette on your Block Diagram.
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  1. Then right-click on the Task and select class > DAQmx > DAQmx Channel. And select Change to Write.Graphical user interface, application  Description automatically generated
Sometimes, when you go to set the properties in a DAQmx Property Node in LabVIEW, the property that you are looking for does not show up in the list of options. To fix the problem, follow this article: DAQmx Property Node is Missing Properties - NI
 
  1. Select the property:
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  1. Right-click on the input terminal and create a control. and Change it to True.
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This can occur on any NI-DAQ device. Devices are especially susceptible at high channel counts and high sample rates. 
 

Additional Information

Internal Buffer Overflow on NI DAQ Device - NI