9205 - Differential channels for grounded signals and floating signals

[edomar]

Hello,

for my application I need to use the analog input module 9205 to measure both grounded signals and floating signals.

The 9205 is used with a cRIO 9057 which is supplied by a 24Vdc power supply.
Some signals to be measured are floating (two wires) and the 9205 should be configured in differential mode. Other signals are single-ended, referred to the 24Vdc power supply "-" terminal (GND). Is it possible to use GND as a second wire of the differential pair and measure the single-ended signals using differential channels?

Thank you

[santo_13]

You can still configure a single-ended signal to be measured differentially as long as you abide by the instrument's common mode voltage and differential voltage limits.

[algarcia]

Hi edomar,

Measuring single-ended signals with differential channels is the preferred method. Take a look at Table 1 on our white paper.

Depending on your setup, measuring a floating signal source in differential mode can present issues with input bias currents on the DAQ input causing the measurement to float out of range.

[edomar]

Thank you for your reply!