Dallas 1820 temperature IC use a true two wire protocol

I would also go for the RS485. (Don't know CAN jet)

I was once experimenting with two 16F84
Only two wires between the master and the slave.(GND and 12V)
Slave had a backup battery

While you dont transmit data  - charge the battery!

Otherwise pulse the 12V Line for data transfer (few bytes every minute
should not be a problem)

Francois


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