Setup for current input without knowing resistance?

[Brad.747]

I know I have a current through an object and need to measure that current. I am using a PCI-6289 DAQ card. The analog input configuration for current requires the resistor value to be inputted. Is there a way to measure the current when the resistance is unknown? What does choosing the option for internal shunt resistor do?

[R Sandoval]

Hello There,

A good practice of measuring current using the PCI-6289 is to place a shunt resistor in series with the object and near ground.  You should then take the voltage measurement across the shunt resistor.  In an acquisition task, you can select current measurement which simply applies Ohm's Law by taking into account of the shunt resistor's value.  This process is described in the following document:

Current Measurements: How-To Guide

http://zone.ni.com/devzone/cda/tut/p/id/7114