Inactive Digital Inputs and Outputs in cRIO-9049 in Scan Interface Mode

Updated Jun 19, 2019

Reported In


  • cRIO-9049
  • NI-9401


  • LabVIEW 2018 Professional
  • LabVIEW 2017 Professional

Issue Details

I would like to read the digital inputs of an NI-9401 in a cRIO-9049 by programming its RT processor in LabVIEW in Scan Interface Mode. I have already set the Program Mode to Real-Time Scan (IO Variables) in MAX. When I run the VI, the inputs are not being read. Similarly, in case I try to set the digital outputs in the same system, when running the VI, the outputs are not being written. At the same time I don't get any error messages.


A possible root cause of the issue is, that the programming mode has not been set properly in LabVIEW.
Make sure it is set to Scan Interface instead of LabVIEW FPGA Interface:
  1. In LabVIEW, in the Project Explorer window right-click on Chassis (cRIO-9049).
  2. In the Chassis Properties window choose category Chassis Configuration.
  3. Select the Scan Interface under RIO Programming Mode and click OK.
  4. To deploy settings, right-click the chassis in the Project Explorer window and select Deploy.
  5. Run the VI.


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