We need to read CAN bus data from vehicles and machinery. How do we choose a CAN port on an industrial PC, and what matters in wiring?

First identify the standard your equipment uses: CAN 2.0A/B (classic CAN): up to 1 Mbit/s, widely used in machinery and vehicles. CAN FD: a faster data phase (typically 2–5 Mbit/s) and longer frames. A CAN FD port can read classic CAN, but a classic CAN port cannot read CAN FD. Higher-layer protocols: SAE J1939 on trucks and construction equipment (usually 250 or 500 kbit/s), CANopen in automated machinery. The hardware port is the same; the decoding software differs. Port selection: prefer an isolated CAN port that comes with a vendor library or driver for your operating system (Windows or Linux SocketCAN). Wiring: 1. Twisted pair for CAN_H and CAN_L, with a shield. 2. 120 ohm terminators at the two ends of the network, and no more. Measured between CAN_H and CAN_L with power off, you should read about 60 ohm. 3. The higher the bit rate, the shorter the cable: about 40 m at 1 Mbit/s, a few hundred metres at 125 kbit/s.