If you download the specifications document for the PXI-2568 from NI's website there is a section close to the end that talks about cabling and accessories. The PXI-2568 uses a standard 62 pin D-sub connector. The cable and terminal blocks for this connector can be found at large electronic suppliers. I hope this helps and have a great day!
Bryan Snarr
Application Engineer
National Instruments
Bryan Snarr
Field Engineer
Northern California
National Instruments