How Does the 9411 Know When It's Differential or Single Ended

Updated Jun 20, 2019

Reported In

Hardware

  • CompactDAQ Chassis
  • NI-9411

Issue Details

Without setting the hardware to differential or single-ended, how does the NI 9411 recognize when one channel wire is removed?  

Solution

In the case of the 9411 reading a differential measurement for the DIA+ and DIA- terminals, the hardware takes the difference of the two inputs and will determine if it's positive (between 300mV and 24V) and negative (-300mV to -24V). 

For single ended mode, only the positive input terminal is wired while the negative terminal is floating. The NI 9411 can then pull the negative line to a set voltage. This allows users to set new input limits for single ended measurements either high (2-24V) or low (0-0.8V)