How Do I Measure Resistance With A 3-Wire Device?
If you are using a 3-wire device (ie. 3-wire RTD), to measure it accurately, you have to first measure the resistance of R1+R2+Rm then subtract the resistance you measured of R2+R3. You can set the instrument to either 2-wire or 4-wire resistance measurement to perform these measurements.
Remember R1, R2, and R3 mean the resistance in the wire leads.