RS-485

TIA-485-A; (Revision of EIA-485)
Standard	ANSI/TIA/EIA-485-A-1998 ; Approved: March 3, 1998 ; Reaffirmed: December 7, 2012
Physical media	Balanced interconnecting cable
Network topology	Point-to-point, multi-dropped, multi-point
Maximum devices	At least 32 unit loads
Maximum distance	Not specified
Mode of operation	Different receiver levels: ; binary 1 (OFF); (Voa–Vob < −200 mV); binary 0 (ON); (Voa–Vob > +200 mV)
Available signals	A, B, C
Connector types	Not specified

RS-485, also known as TIA-485(-A) or EIA-485, is a standard, originally introduced in 1983, defining the electrical characteristics of drivers and receivers for use in serial communications systems. Electrical signaling is balanced, and multipoint systems are supported. The standard is jointly published by the Telecommunications Industry Association and Electronic Industries Alliance (TIA/EIA). Digital communications networks implementing the standard can be used effectively over long distances and in electrically noisy environments. Multiple receivers may be connected to such a network in a linear, multidrop bus. These characteristics make RS-485 useful in industrial control systems and similar applications.

TIA-485-A (Revision of EIA-485)
Standard	ANSI/TIA/EIA-485-A-1998 Approved: March 3, 1998 Reaffirmed: December 7, 2012
Physical media	Balanced interconnecting cable
Network topology	Point-to-point, multi-dropped, multi-point
Maximum devices	At least 32 unit loads
Maximum distance	Not specified
Mode of operation	Different receiver levels: binary 1 (OFF) (Voa–Vob < −200 mV) binary 0 (ON) (Voa–Vob > +200 mV)
Available signals	A, B, C
Connector types	Not specified