Can I connect CANbus nodes in a star/split configuration?

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Hi new around here, so hello to you all AVRfreaks.

As the topic says, is it possible to connect CAN nodes in a star or split (physically) configuration, instead of the typically chain configuration?

E.g. Say I have a project for one customer and start with a normal chain configuration with several nodes and the terminate resistors at both ends. So far nothing special, but after a few years that customer wants to upgrade his system with a few other nodes. Now those nodes will be placed 300-400 feet away from the closest existing nodes. To avoid two times the length of the data cable and in meantime losing some transmission speed , is it possible to connect at one point in the chain making a split connection and terminate that connection with bigger (say 1k) resistor after the last added node?

I know I could use repeaters for lengthening the distance and keeping the transmission speed, but I want to keep it ‘simple’ and not too expensive. I know some RS485 systems are allowed to use split connections (like LonWorks).

Will I need a repeater/driver anyway?

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Hase anybody an idea, or maybe I did not explain verry good? I am not the best in explaining things :?

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You're aware, of course, that that would go against CAN specifications. Depending on the speed of your bus, however, it could work. I am not sure on the specifics (ie size of terminating resistor and all of that stuff) - but CAN is fairly tolerant of that stuff.

Thing is, if this is for a client, I really don't think it's a good idea to go against spec. I think a CAN repeater would be a good idea. I have never used one myself, but this one looks promising: http://www.amis.com/products/tra...

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Hi, thanks for the reply.

I already thought the 'client or customer' thing was a bit over the edge on this forum, but it was more to put the problem in a real world situation.

I just want(ed) to know if, on the hardware side, it is possible to split the CANbus. And if it’s possible what do I need to change or add on the transceiver side and eventually on the software side.

I work in the refrigeration business and often have to deal with Danfoss cold room controllers, it uses the RS485 serial protocol for communication between controllers, and with their system you can split the data bus. I always thought that it was not possible, even with the RS485 bus, but apparently I am wrong.