BACnetEd: Created page with "'''Attempting to reduce RS-485 polarity issues to fundamental reasoning * A>B means "binary 0 on the bus" or "ON" - from the standard * "MARK" state (no transmitters enabled) is defined by line biasing, and sets A>B, and this is "Idle" * UARTs output a logic '1' (high voltage) for Idle state! * A is non-inverting (+), B is inverting (-) Done"

2026-10-04T15:15:33Z

Created page with "'''Attempting to reduce RS-485 polarity issues to fundamental reasoning * A>B means "binary 0 on the bus" or "ON" - from the standard * "MARK" state (no transmitters enabled) is defined by line biasing, and sets A>B, and this is "Idle" * UARTs output a logic '1' (high voltage) for Idle state! * A is non-inverting (+), B is inverting (-) Done"

New page

'''Attempting to reduce RS-485 polarity issues to fundamental reasoning

* A>B means "binary 0 on the bus" or "ON" - from the standard
* "MARK" state (no transmitters enabled) is defined by line biasing, and sets A>B, and this is "Idle"
* UARTs output a logic '1' (high voltage) for Idle state!
* A is non-inverting (+), B is inverting (-)

Done

RS-485 Polarity First Principles - Revision history