Why is There Resistance When Connecting Channels Using PXIe-2532B and TB-2644B?

Updated Mar 25, 2025

Reported In

Hardware

  • PXI-2532B
  • TB-2644B

Issue Details

I have a PXIe-2532B connected with a TB-2644B. When I connect the 'B0R0' and 'B0C0' channels using the NI-SWITCH Soft Front Panel and then measure the resistance across these channels with a DMM, I observe a resistance reading of 200Ω. Why is this happening?

Solution

TB-2644B has 100Ω row and column protection resistors. Therefore, it is expected to see a 200Ω resistance reading on your DMM.

Additional Information

The resistor is used to isolate the unwanted effects of the load capacitance and limit damage to the relay contacts, such as inrush current. If you want to bypass the row protection resistors, please refer to NI TB-2644B Installation Instructions and Specifications.

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