Solution
There are two ways to download NI-RIO, depending on what version you need.
NI-RIO 14.5 or ealier:The older versions of NI-RIO drivers are available as a separate download from our website. You can search for "NI RIO XX.X", with the version number inserted in place of the XX.X, to find the correct page.
This page is where you would download the most recent version of stand-alone NI-RIO drivers.
NI-RIO 15.0 or later:As of the 15.0 version of the drivers, there are separate downloads for each of the 3 types of RIO devices:
Each of these includes specific drivers and services needed to run its respective type of hardware, as well as some components that are common to all three types. These shared components are listed in NI MAX as NI-RIO, and are included in the installer for each of the specific types of RIO devices.