Resistance Measurements (2 and 4 wire)

The GX2065 has seven ohms ranges to measure resistance from 100µ ohms to 100M ohms. Available measurement ranges include 100 ohms, 1k ohms, 10k ohms, 100k ohm, 1M ohms, 10M ohms, and 100M ohms. The GX2065 can perform both 2 and 4 wire resistance measurements.  Two wire measurements use the Hi and Lo terminals and four wire measurements use the Hi, Lo, Sense Hi, and Sense Lo terminals. For resistances >1k ohm, the 2-wire function is typically used for measurements. For resistances less than 1 K ohm, the 4-wire function is typically used which cancels the effects of test lead (and channel path) resistances.

For the 100 ohm to 1M ohm ranges, the GX2065 uses the constant-current method to measure resistance.  A constant current is sourced to the unknown and the voltage across the unknown resistance is measured. Resistance (R) is then calculated using the known current and measured voltage (R = V/I). For the 10M ohm and 100M ohm  ranges, the ratiometric method is used to measure resistance which employs a test current (0.7µA source) in parallel with a 10M reference resistor and the unknown resistance value. Knowing the value of the source current and the 10 M ohm reference resistor, a radiometric calculation can be made as determined by the following equation:

ISOUR = (VMEAS / RREF) + (VMEAS / RDUT)