The PEX-P64 (-24V) supports PCI Express bus. These cards provide 64 optically isolated digital input (DI) channels that use either an internal or external power supply that can be selected via a jumper. The internal power is provided by an onboard isolated DC/DC converter that provides 3000 VDC isolation and is used for connecting dry-contact input devices. These DI channels are arranged into four isolated banks when using four isolated external power supplies.