USB 9219 Voltage and 4-wire modes

[vt92]

I have a USB 9219 and I would like to use both the Voltage measurement and the 4-wire resistance modes without changing any wiring between measurements. 

According to the manual, I need to use pins 4 and 5 for voltage, but I already have 4 and 6 wired as inputs for the 4-wire measurement.  When I try to take a voltage measurement using pins 4 and 6, instead of 4 and 5, I get an voltage offset error. 

I don't understand why they swap EX- and LO depending on the mode, since HI doesn't change between the two modes I'm interested in.

Any suggestions?

[GarPar]

Hi vt92-

     If you set up the NI 9219 to perform a Custom Voltage with Excitation task, it uses pins 4 and 6 for the actual measurement (as opposed to pins 4 and 5).  You can then switch between 4-wire resistance and Custom Voltage with Excitation without changing any wires between the two tasks.  You just won't be using the excitation channels (you can set the excitation level fairly low).

     This should work.  Best of luck with your application!