Error -201421 Using the Test Panels or a DAQmx Task

Updated Jan 24, 2019

Reported In


  • NI-9218


  • Measurement & Automation Explorer (MAX)
  • LabVIEW

Issue Details

I am using the Test Panels or a DAQmx Task in Measurement & Automation Explorer (MAX) or LabVIEW to configure a current analog input task. I know my device's accessory has a built-in shunt resistor for current measurement but when I run the acquisition, I get error -301421 suggesting my device's accessory does not support the configuration. How do I configure my accessory appropriately to avoid this error?

Error -201421 occurred at daqmxcfg_DAQmx Start
Possible reason(s):
The accessory attached to the device does not support this property.
Property: AI.CurrentShunt.Loc
Requested Value: Internal
Possible Values: External
Channel Name: cDAQ1Mod1/ai0
Accessory Type: None


This error can occur with devices that have different accessories for different measurement types whenever the correct accessory has not been configured. For example, the NI 9218 Datasheet describes the accessories needed by the module for different measurement types. As a more specific example, the NI 9218 needs an NI 9983 accessory for a current input task.

To configure the correct accessory in your device:
  1. Right-click your device in NI MAX and select Configure....
  2. Set the Accessory field to the right value and click OK. For example, select one of the NI 9983 variations to make current measurements with an NI 9218.
  3. NI MAX should display the accessory under the module as seen in the screenshot below.

Once this is done, the error should not show up.