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Unread 21-10-2015, 20:13
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Re: Terminating Resistor CAN

Quote:
Originally Posted by CortEnis View Post
According to my experience the CANBus will have 120Ω across CANH and CANL at each of the ends.
This gives a measured 60Ω between CANH and CANL.
When the CAN transceiver in a CAN node drives dominant the transceiver provides high and low voltage across the termination resistors.
For bench top use, if your bus is short you can probably get away with just one side terminated.
The #1 problem with this setup is that it draws twice as much current as the transceiver is designed to deliver. I would expect it to shorten the transceiver life, at least. The #2 problem is signal reflection from the "open" end. With short runs, the reflected signal level is probably well below the actual signal, and you'll do OK. As the bus gets longer, the difference between the reflected and direct level (that is, the signal to noise ratio) degrades.
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