Error -200946 Using a NI DAQ Device

Updated Feb 11, 2020

Reported In

Software

  • LabVIEW

Driver

  • NI-DAQmx

Issue Details

  • I get error -200946 when using my USB DAQ device.
  • The error is intermittent, or doesn't always happen within the same time frame.
  • This message sometimes happens when my application has been running for a long time.
 


Error -200946 occurred at Untitled 1

 

Possible reason(s):

 

Task could not be started, because the driver could not write enough data to the device.  This was due to system and/or bus-bandwidth limitations.

 

Reduce the number of programs your computer is executing concurrently.  If possible, perform operations with heavy bus usage sequentially instead of in parallel.  If you can't eliminate the problem, contact National Instruments support at ni.com/support.

Solution

This error can occur for a number of reasons. Typically the USB bus is a shared resource for many laptop and desktop computers, due to this, the bus can have a lot of activity. On top of this the USB bus communication can be dependent on other process with higher priority. 

It is also possible that your application is trying to write to quickly to the device. As USB is not a deterministic bus trying to push high data throughput's can result in this error.  

  • Try disconnecting other USB devices
  • On Desktop PC's plug the USB DAQ device into ports with direct connection to the motherboard (likely on the back of the PC). For laptops, try different USB ports, as each laptop varies in topology. 
  • Read/write slower to the device.
  • Trying reducing the number of applications running on your system to free up CPU resources. 

If you're using a virtual machine, refer to the article Are NI Products Supported on Virtual Machines (VMs)?

Additional Information

The error happens because the communication bus is not responding as fast as needed.

You may look to modify the priority that you are assigning the USB bus, however that may vary given your CPU and OS.