9411 Cabling - Impedance Matching

[9Ra26M]

What is the recommended characteristic impedance of the cable used to connect a sensor to to the NI 9411's differential DIa/DIb channels? Would either 100 ohm or 120 ohm be appropriate?

[croohcifer · Accepted solution]

There isn't a recommended cabling impedance because the signal frequencies that device supports are far too low for reflections to be a problem.  See here:  https://electronics.stackexchange.com/questions/178112/why-do-characteristic-impedances-matter-only-...

You could match the cable impedance to your signal source's output impedance if you really wanted to, but you'll still have a discontinuity when the signal reaches the 9411's 8.4 kOhm input impedance.  Again, this is not a problem.  Use whichever cable you want.