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How many nodes can one have on a single CAN bus

Erich
Prodigy 210 points
Other Parts Discussed in Thread: SN65HVD231, ISO1050

I am no expert on CAN, but would like to know whether it is possible to have (say) 200 to 300 device nodes on a single CAN bus.  I have seen on data sheet of eg SN65HVD231 that 120 nodes can be supported.  Is there some way to extend the number of nodes by using a repeater of sorts?

Any sugegstions most welcome.

  • 0
    TI__Mastermind 28265 points

    This is a longer answer which our CAN specialist Scott Monroe answered numerous times in the forum and on ESP.

    it basically depends on a lot of factors, one of them being the loop time during arbitration during which a bit (sent by as driver) has to travel to the farest receiver and back to the driver. The prop-delay of the link is then dependent on the number of nodes and their capacitances, the type of cable, etc.

    So yes it is possible to extend the number of nodes  by drastically dropping the data rate and using transceivers with small input capacitance. I believe the most nodes we accomplished so far were 162.

    unfortunately Scott is on vacation and back next week. - Thomas

  • 0 in reply to Thomas Kugelstadt
    TI__Mastermind 20580 points

    That is a correct summary Thomas.  For additional scaling and network design references a lot of this has been done in standardization bodies such as CANopen, DeviceNet, ARINC825, etc where these groups have set rules on wiring, connectors, topology, termination, etc and then set a guideline for number of nodes vs cable length vs data rate.  Essentially the longer and more nodes you have the slower you will have to be at the data rate.  A more detailed description on this topic has been updated into the ISO1050 CAN datasheet and will ultimately be edited into future revisions of the HVDxxx CAN datasheets.  Please see page 21-22 of the ISO1050 DS (http://www.ti.com/lit/ds/symlink/iso1050.pdf) for this description of CAN bus nodes, length and data rate. 

    -- Scott