usb6009 connection to transducer

[j^2]

I am utilizing a USB6009 to capture analog voltages from a pressure transducer. The transducer voltages are conditioned 0.5V to 4.5V for the 5V power model and 0.5 to 5V for the 12V power model. Which connection to the 6009 should I use? RSE or diff and if diff, what bias resistor sizes? If it helps, I am using an Optrand sensor. Also, what model would be best suited for me? The 5V or 12V model? If I go with the 5V I can utilize the 5V bus and ground on-board the 6009. If 12V, then I will use a regulated 12V supply but the reference ground is where I get confused.

[enderWiggin10]

Hi j^2,

In situations like this, it typically helps to post images of the sensor wiring diagram, or at least link the schematic/datasheet.  

The USB-6009 can handle analog input from +10V to -10V, and it actually has a range of +/-5V, which would give you better resolution for your signal.  Almost always, you will want to use differential input when it is possible.  this allows you to eliminate common mode voltages and noise.  Bear in mind that the +5V DC Power rail can only source up to 200mA maximum, and the voltage level is not guaranteed to hold at 5V, but can range from 4.85 to 5V.  However, 1 pressure transducer should not draw more than 200mA, and the sensor should also be able to handle slight variations in the voltage supply.

Another thing to check on is if the pressure sensor, is if it is a bridge sensor or not.  If it is a bridge sensor, you might want to consider measuring your supply voltage to the bridge.  This is discussed in the following document for the NI myDAQ, but the theory applies here as well.

Best,