Almost every PC CAN interface, logger and gateway uses a 9-pin D-sub with the pin assignment recommended by CAN in Automation (CiA). Here is the layout, which side is male, and how to wire it to vehicle connectors.
Pin 7 is CAN High, pin 2 CAN Low and pin 3 CAN ground. Pins 5 (shield), 6 (ground) and 9 (supply) are optional; 1, 4 and 8 are reserved. Switch between the male and female face — the numbering is mirrored.
Face view of the male (pin) connector — the side on most interfaces
| Pin | Signal |
|---|---|
| 1 | Reserved |
| 2 | CAN Low |
| 3 | CAN ground |
| 4 | Reserved |
| 5 | CAN shield — Optional |
| 6 | Ground — Optional |
| 7 | CAN High |
| 8 | Reserved |
| 9 | CAN_V+ supply — Optional; voltage is device specific |
| Recommendation | CiA 303-1, now consolidated in CiA 106 (2023) |
|---|---|
| Required pins | 7 CAN High, 2 CAN Low, 3 CAN ground |
| Optional pins | 5 shield, 6 ground, 9 CAN_V+ supply |
| Interface side | Male (pins) on most interfaces and loggers |
| Cable side | Female (sockets) on most adapter cables and terminators |
| Bit rate | Set by the bus, not the connector — classic CAN and CAN FD |
The 9-pin D-sub assignment was the first connector recommendation CAN in Automation published, originally as CiA DS 102 and later in CiA 303-1, the CANopen cabling and connector recommendation. In 2023 CiA moved all its connector pin assignments into CiA 106, which applies them to classic CAN, CAN FD and CAN XL alike.
The D-sub was already everywhere as a PC serial connector, and the CiA layout became the de facto standard for PC CAN interfaces — which is why most vehicle adapter cables end in a female DB9.
Pin 9 is an optional supply input, and its voltage is device specific: some loggers accept vehicle battery (for example 7–32 V), while many PC interfaces leave it unconnected. Some vendors also put a second CAN channel on reserved pins 4 and 8. Check the device manual before wiring anything beyond pins 2, 3 and 7.
Choose any two connectors to get a pin-to-pin wiring diagram, with wire colours, which pins to leave unconnected, and the power and termination warnings that matter. Hover a wire to trace it.
Pick two connectors to draw the wiring. (Needs JavaScript.)
Following CiA: pin 7 CAN High, pin 2 CAN Low, pin 3 CAN ground. Pin 5 (shield), 6 (ground) and 9 (supply) are optional, and pins 1, 4 and 8 are reserved.
No. They share the connector shell only. RS-232 uses pins 2 and 3 for data and 5 for ground, so connecting the two will not work and can put supply voltage on signal pins.
It is the optional CAN_V+ supply. Some loggers and adapters take vehicle battery on pin 9; many PC interfaces leave it unconnected. Check the voltage your device accepts.
Interfaces normally have a male DB9 (pins); cables, adapters and terminators normally have a female DB9 (sockets).
Only if the interface sits at a physical end of the bus and that end is not already terminated. A healthy bus reads about 60 Ω between pins 2 and 7 with power off.
Sources: CiA 106 connector pin assignment; HMS / Ixxat CAN connector pin reference; Kvaser PCIEcan user guide (D-sub 9); Wikipedia: CAN bus; NI: CAN OBD-II cable specification; CSS Electronics: J1939 to DB9 cable pinout.
Last reviewed 2026-10-27. Pin assignments follow CiA 303-1 / CiA 106; OEM variants are noted where we could verify them. Spotted an error? Tell us.
iMatrix designs and builds CAN, J1939 and OBD-II harnesses for OEMs and fleets, and our FleetConnect telematics devices plug straight into the 9-pin and OBD-II ports. Tell us the two ends and the quantity.
