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NI 9411 Quadrature Encoder LabVIEW FPGA Example Code

Updated Aug 14, 2019

Reported In


  • NI-9411
  • cRIO-9012
  • cRIO-9112


  • LabVIEW

Operating System

  • Windows

Issue Details

I would like to use three NI 9411 modules in CompactRIO scan mode for reading quadrature encoder input functionality. However, CompactRIO chassis is in Scan Interface programming mode supports up to only two slots for specialty digital functions. So I am moving to LabVIEW FPGA Interface programming mode. Are there any LabVIEW FPGA example programs for reading quadrature encoder input signals?


The attached example program demonstrates how to estimate velocity and acceleration of a Quadrature Encoder by using LabVIEW FPGA and CompactRIO. The example consists of an FPGA VI, Encoder Position & Velocity (FPGA).vi, which will run on the FPGA platform and a host VI, Encoder Position & Velocity (Host).vi, which will run on the Host Machine. The example program was designed for a PXI-7811R FPGA and an R Series expansion chassis with a cRIO-9411 DI module in slot 1.

Additional Information

The attached vi can easily be modified to run on any other cRIO FPGA platform.