Solution
There is no datasheet for the NI CAN Breakout Box. The Breakout Box is mostly passive, providing the ability to connect CAN devices to a bus, probe specific CAN wires using the breakouts, and provide bus power.
Some information, such as the connector pinouts and input power requirements, are printed on a label on the bottom of the device itself. Here is a copy of that label:

This device can be used without connecting a power supply if it is connected to a CAN bus that is already powered. If you need to supply power, refer to these specifications:
- Input voltage range: 8-30VDC
- Input current: 1A max
- Use an energy-limited power source (LPS)
In addition, here are the types of connectors used on this device:
- CAN ports - DB9 Male
- Breakout terminals - Combicon HDR 5pos 5.08mm
- Power connector - 0.080" DC locking Power Jack