National Instruments NI 2590/2591 - Manual (Page 14)

Chapter 1 Routing Signals with Your NI 2590/2591
NI 2590/2591 User Manual 1-6 ni.com
Third-Party Software
The NI-SWITCH instrument driver also includes support files for
Microsoft Visual C++ and Microsoft Visual Basic. See the NI-SWITCH
Software Readme File for version support information.
Cabling and Accessory Requirements
National Instruments recommends the use of cables and accessories with
50
Ω characteristic impedance with the NI 2590/2591.