CANBUS cable

5687 Views 9 Replies 5 Participants Last post by MemphisPapa, Oct 28, 2012

MemphisPapa

Discussion Starter · Oct 22, 2012

So I have been back and forth with a Chinese company (cough-BestGo-cough) about a charger that won't pick up the message to begin a charge cycle. My BMS is getting the CAN message and I can see the CAN message going to the charger. My BMS support has pointed out that not all CANBUS transceivers are created equal. I suspect that my cheap Chinese charger has a cheap transceiver and is unable to pick up the messages over my dirty cable. I have chopped the stubs to only 8" and have soldered all my wire connections. I have a BT scan tool that is working okay with Torque. All my communication with my BMS is over the CAN which works fine too. I can actually see the message from the charger that shows the communication failure. Does anyone have a special technique to build a solid CANBUS cable that might help resolve my cheap charger issue? Evidently, the charger won't work unless the CAN message is received by the cheap charger transceiver... lesson learnt, buy American.
Thanks.
dh

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Semper Vivus

· #2 · Oct 22, 2012

Hello,

I assume the termination of the bus is done right (120 Ohms etc..)?
Do you have connected the ground to the charger or only CAN low and CAN high?
Do you have a scope to check the quality of the signal?
Are you sure the CAN Message to the charger has the right format (ID, DLC...) and the right data?

One twisted pair of an ethernet cable should work fine, if you don't want to buy a special CAN cable.
Don't route power cables in parallel to the communication wires.

Kind regards,
Tom

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Semper Vivus

· #5 · Oct 22, 2012

In my opinion the best solution for the stubs would be a M12 T-Connector like that:
http://www1.lumberg-automation.de/main/common/serie_.asp?lang=eng&cat=3&ser=A11&cat3=_3
But than you need other cabling I think

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Semper Vivus

· #6 · Oct 22, 2012

frodus said:
I know there's some problems with Elcon... Maybe this is similar?

http://lithiumate.elithion.com/php/elcon.php

"CAN module built before July 2011 cannot handle being on buses that contain more than 2 messages per second!"
-> Sounds bad. Maybe that is the reason why your charge only sends out error messages?

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