Timeline for Quick question regarding CANbus wiring
Current License: CC BY-SA 4.0
6 events
| when toggle format | what | by | license | comment | |
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| Sep 21, 2021 at 15:15 | comment | added | Davide Andrea | OK, I looked up in ISO 11898-2, "Road vehicles — Controller area network (CAN) — Part 2: High-speed medium access unit" iso.org/standard/67244.html. It says: "two-wire cable, relative to a common ground". You are correct, I stand corrected. | |
| Sep 21, 2021 at 13:56 | comment | added | Lundin | @DavideAndrea There also exists a quackery myth that you don't need to have signal ground across nodes located on the same vehicle, but people saying such cannot possibly have worked with automotive electronics in a professional setting, since the chassis ground is noisy as f*** and can't be used as signal reference, because that ground will be shared with starters, alternators, valves and all other evil things that could be found on some generic vehicle. | |
| Sep 21, 2021 at 13:54 | comment | added | Lundin | @DavideAndrea No, CAN is a 5 wire bus where shield and V+ are optional. Fundamental electronics knowledge gives that for example your PC and a car will not necessarily have a voltage potential difference that's within the spec of the CAN transceiver. Which is +/-58V on modern CAN transceivers like MCP2562FD and far less on older ones like TJA1050 or MCP2551. Thus we need a signal ground or the communication might fail. | |
| Sep 16, 2021 at 13:50 | comment | added | Lundin | @Ben Maximum recommended stub length is still around 0.3m then. And you still need a signal ground. | |
| Sep 16, 2021 at 9:52 | comment | added | Ben | Thanks for your answer. To make it more understanding: the bus i want to connect on is already a working system. i just want to add one sensor, and its very close-by to another sensor. So the system is functional and working. The system is SAE J1939, so speed is between 250-500 kbps. | |
| Sep 16, 2021 at 9:48 | history | answered | Lundin | CC BY-SA 4.0 |