Configuring the Flyback Diodes of a PXI-2567 For an External Power Supply

Updated Apr 3, 2023

Reported In


  • PXI-2567

Issue Details

I am planning to use a PXI-2567 to drive relays, but I want to use an external power supply instead of the internal sources from the card. How do I configure the relay driver card's flybacks to route to the correct power source?


The flyback diodes on a PXI-2567 neither can nor need to be configured. They are internal to the card and are set in parallel with each channel’s circuitry to protect the card’s channels, regardless of whether the power source is internal or external to the card. The NI PXI-2567 Hardware Diagram topic in the NI-Switches Help shows a flyback diode in each channel.

Additional Information

When you are driving an inductive load through a switch, a phenomenon known as flyback will cause a sudden voltage spike, which can be much larger than the supplied voltage, when the switch is opened power is interrupted. This voltage can damage the circuity on a switch, so the flyback diodes were included on the PXI-2567 to prevent this damage.