CAN adapter termination

Peter Carroll/Toronto
Posts: 110
Joined: Wed Jul 04, 2007 11:33 pm
Location: Toronto, Canada
Contact:

CAN adapter termination

Postby Peter Carroll/Toronto » Mon Jul 26, 2010 2:46 am

I think a lot of customers are missing the importance of terminating the CAN bus.

Since the vast majority of users will only have their ECU and CAN adapter on the bus, would it not make more sense to have a terminating resistor built into the CAN adapter? Then 99% of the people that need it would have it out of the box.

For the 1% of people that would not want it terminated, you could leave a small loop of wire out the end of the box we can cut. Or we could just open the box and cut a resistor.

I think this would save a lot of messing around and support headaches...
Peter Carroll, Toronto, Canada
DL1 and Dash2 - http://DriversMeeting.com/pcarroll

Support

Postby Support » Fri Jul 30, 2010 12:59 pm

Although it is true that a termination is required in a lot of applications, it is much safer to supply a system without the termination, since plugging this in will not stop the existing system from working. If all units were supplied with termination then it could well cause problems on some systems.

Peter Carroll/Toronto
Posts: 110
Joined: Wed Jul 04, 2007 11:33 pm
Location: Toronto, Canada
Contact:

Postby Peter Carroll/Toronto » Sat Sep 04, 2010 3:17 pm

Then I suggest adding the terminator internally in the CAN module (not the DB9 connector) and leaving two wires hanging from the case with instructions to join them if you need termination.

I opened the CAN Adapter case and soldered a resistor across the can pins.

I would also edit the section in the manual to describe how to use a volt meter to measure the static resistance of the connectors to determine if the terminator is present in the system or not. Currently, it describes the intended circuit but a less electronics inclined customer may not know how to check for it. It's not like you can always see the terminators in other equipment.
Peter Carroll, Toronto, Canada
DL1 and Dash2 - http://DriversMeeting.com/pcarroll

maol
Posts: 2
Joined: Mon Jun 03, 2013 10:42 pm

Postby maol » Tue Jun 04, 2013 10:38 am

I agree. I am currently trying to install the CAN Adapter but
am finding the bit about terminating the CAN confusing. Could
somebody please explain if the 120 ohm resistor should be on
the side nearest to the ECU or the DL1 if it is soldered inside
the CAN Adapter?

Magnus, Norway

racetec
Site Admin
Posts: 193
Joined: Thu Oct 27, 2005 12:02 pm

Postby racetec » Tue Jun 04, 2013 12:10 pm


maol
Posts: 2
Joined: Mon Jun 03, 2013 10:42 pm

Postby maol » Tue Jun 04, 2013 2:12 pm

Thank you for the quick response.

Does this mean that if I connect the CAN H/L to the ECU I do not
need to worry about terminating the CAN? That the resistor fitted
to the DB9 connector will provide the termination and no further
steps are necessary?

Magnus, Norway

racetec
Site Admin
Posts: 193
Joined: Thu Oct 27, 2005 12:02 pm

Postby racetec » Wed Jun 05, 2013 10:44 am

Hi Magnus,

Yes, that's correct.

Kind regards,

RT support.


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