CAN bus cable and wiring?

JRDM

I can't find resources on what it takes to make a CAN bus wire for the Duet3 line. I'm looking for wire and cable spec recommendations, and pinouts on said page would be handy too. Also, the Duet3d retail site and a couple resellers that I checked didn't seem to offer anycables separately.

Veti

https://duet3d.dozuki.com/Wiki/Duet_3_Mainboard_6HC_Hardware_Overview
see
The CAN BUS is connected via RJ11 and at least 2 core twisted pair, although 6 core RJ11 is more common.

rj11 are standard cables that you can buy anywhere

dc42

The spec is unshielded twisted pair with 120 ohms impedance. Here in the UK, "High speed ADSL" or VDSL cables are suitable. Here is an example: https://www.kenable.co.uk/en/search?controller=search&search_query=high+speed+adsl+cable. RRF uses one pair, connected to the middle two pins of the 6-way modular connector.

In practice, if the cable lengths are short and you have only a few boards on the CAN bus, you can get away with lesser specifications, such as untwisted RJ11 telephone cable. I have also used telephone/alarm cable during testing.

JRDM

@dc42 said in CAN bus cable & wiring?:

The spec is unshielded twisted pair with 120 ohms impedance. Here in the UK, "High speed ADSL" or VDSL cables are suitable. Here is an example: https://www.kenable.co.uk/en/search?controller=search&search_query=high+speed+adsl+cable. RRF uses one pair, connected to the middle two pins of the 6-way modular connector.

In practice, if the cable lengths are short and you have only a few boards on the CAN bus, you can get away with lesser specifications, such as untwisted RJ11 telephone cable. I have also used telephone/alarm cable during testing.

OK. It does seem the *DSL cables are 100ohms impedance. Will this work for a chain that's 5 or 6 devices, totalling 4 meters?

dc42

@JRDM said in CAN bus cable and wiring?:

OK. It does seem the *DSL cables are 100ohms impedance. Will this work for a chain that's 5 or 6 devices, totalling 4 meters?

Yes, that should be OK.

Nuramori

@dc42

One request i would make is a future hardware change - add a jumper configurable “end of chain” resistor. I understand how the tool board was designed for use with the distribution board, but the tool board is extremely useful for single headed printers too. The termination resistor is kind of documented for this implementation of a tool board, but I can see it’s popularity by reducing wiring making it a popular approach. Allowing for wiring it up and then changing a jumper would make it much easier.