Hi best_blue,
If you are measuring 0.008Ω, you'll want to perform a 4-wire resistance measurement. This prevents the path resistance from offsetting the measurement. You could choose the PXI-2529, as it provides a 2-wire matrix topology, enabling you to connect DMM HI, DMM LO, DMM HI SENSE, and DMM LO SENSE to two rows (R0+, R0-, R1+, and R1-) and to connect every two columns to each resistance under test, i.e. C0+ to res+, C0- to res-, C1+ to res+, C1- to res-.
However, I would recommend using a 4-wire Multiplexer switch module, including the PXI-2501, PXI-2503, PXI-2527, and PXI-2530. The PXI-2576 would also work great in its 2-wire Dual 32x1 Multiplexer topology. For unlimited lifetime, you may even want to consider the PXI-2535 in its 1-wire 4x136 Matrix topology.
Additional Questions
How many channels do you plan to measure?
8 mΩ is not a large resistance. How accurate do you require the results to be?
Are there any other requirements in your application we can use to determine the ideal switch module?
The most current that the PXI-4071 will provide is 100 mA in its 100 Ω range. You may want to consider using a power supply to apply a larger current and use the PXI-4071 in its voltage mode to achieve greater accuracy (watch out for resistor self-heating though, as the more current you provide, the higher resistance you will measure).
Hope this helps!
Chad Erickson
Switch Product Support Engineer
NI - USA
