Many embedded controllers have a micro-GPIB connector instead of a full-sized connector to save space. The part number for the micro GPIB to GPIB cable is 183285-01 (for the 1m cable) or 183285-02 (for the 2m cable).
The easiest way to find these parts is by looking at the Accessories section of the controller of your choice as an example "Accessories" of the PXIe-8840 check under "Cables and Adapters"