How Many Modules Can I Configure for Specialty Digital Functions in RIO Scan Interface?

Updated Apr 17, 2018

Reported In


  • CompactRIO Chassis


  • LabVIEW
  • LabVIEW Real-Time Module
  • LabVIEW FPGA Module


  • NI-RIO
  • NI CompactRIO

Issue Details

I have configured my Digital Input or Output C Series module for specialty digital functions in a CompactRIO using Scan Interface.  However, when deploying, I receive the following error message:
In Scan Interface mode, you can configure only two slots for specialty digital I/O. If you want more specialty digital slots, add an FPGA target under the chassis to put the chassis in LabVIEW FPGA interface mode.
Can I configure more than two modules for specialty digital functions in Scan Interface mode?


If the CompactRIO chassis is in Scan Interface programming mode, you can configure modules in up to only two slots for specialty digital functions.

There are two prebuilt specialty digital blocks in the RIO Scan Interface, which provide high-speed counter, pulse width modulation (PWM), and quadrature encoder input functionality to any eight channel (or fewer) digital C Series Module.

If you want to configure more than two modules for specialty digital functions, you must change the programming mode of the chassis to FPGA Interface mode.  However, you can still use the Scan Interface for two supported individual modules configured for specialty digital functions even if the chassis you are using is in FPGA interface programming mode or does not support Scan Interface programming mode.  For more information about using Scan Interface mode with individual supported modules, please see Using the Scan Interface with Individual Modules Help Documentation.