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Refering to below link.

https://mbed.org/handbook/CAN

enter image description here

1) Can I use the same diagram on breadboard? I mean the Can bus part (connection A in pic) - where two wires are connected with two 120 ohm resistors? Does this bus need any external voltage supply or I can connect on breadboard as it is. And then from (connection B) nodes will be added to the bus.

2) Also I read that DE9 is used for CAN bus implementation. Can someone let me know how the CAN bus will be implemented with DE9 i.e. above implementation with DE9.

Gaurav K
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  • Comment about CAN BUS wires: the resistor is there to prevent echo. CAN BUS is based on UART / RS485, differential serial communication and side-taps should be as short as possible. Those resistors are like *terminators* to prevent signal to be echoed (propagating back and corrupting the communication). – firda Aug 23 '14 at 10:58
  • @firda So .. is it like just a circular loop ? As shown above and I just need to connect `MCP2551 CANH and CANL` to the `L` and `H` of the bus? Or any additional circuitry required? – Gaurav K Aug 23 '14 at 11:08
  • I am not a hardware designer (but software = programmer, I have people to solve HW issues), but from what I know, this resistor should be as close as possible to your MCU to prevent the signal propagating back (the resistors will swallow any mirroring). Don't know how to say it in better words. Think about antena and NC wire, the signal gets mirrored back on open end, but terminated on closed end (or at resistor). This is the reason for the resistor. But again, I am not a hardware designer, sorry. (I use CAN on ATSAM7XC256 and the resistor is not necessary if your side-tap is extra short.) – firda Aug 23 '14 at 11:14
  • P.S.: We use some chip between MCU and CAN wires as well, possibly to translate voltage and to prevent overcurrent burning MCU. – firda Aug 23 '14 at 11:17
  • @firda Ya that is CAN Tranciever.. in this case MCP2551.. – Gaurav K Aug 23 '14 at 11:25

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