The Deutsche 9 pin(gree,type2) connector in heavy-duty vehicles outputs the following protocols. Connector pin C,D is used for J1939@500kbps, pin F,G is used for J1939@250kbps and H,J is used for CANH&CANL. Since J1939 is a higher layer CAN protocol, does it mean that all these pins are connected to a single BUS?
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\$\begingroup\$ I don't think it does. I recall on one BMW wiring diagram I saw several separate CAN buses called F-CAN, K-CAN, D-CAN and a bunch of others, including LIN and single wire variants. Since they connected different module groups my guess would be they are different. There could be some bridge module there, but since the speeds are different slower buses cannot possibly deliver all the traffic on the faster ones. \$\endgroup\$– MapleCommented Oct 11, 2019 at 8:28
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It simply means that someone picked very bad signal names for the 9 pin connector, in order to confuse everyone. From what I can tell:
- C "J1939+" would be CANH, a signal used in CAN.
- D "J1939-" would be CANL, a signal used in CAN.
- E shield
- F "J1708+" would be B+, a signal used in RS485.
- G "J1708-" would be A-, a signal used in RS485.
As far as I can tell, H and J are OEM specific signals.
Apparently "ODB type 2" connectors may have either RS485 or CAN on the same pins, F and G.
