RS-485 and RS-232 are a type of communication protocol or a type and cable?

I studying these serial communication protocols and each place refers to the RS-232 / RS-485 in different ways. Some articles mention that it is a cable, the other a protocol, so I was in doubt.


RS-232 etc mean different things in different contexts. More specifically it is called TIA/EIA-232.

It refers to both the electrical characteristics of an NRZ signalling system, and at the same time it refers to the packet format for the transmission of data through such a system.

It also refers to the connectors that are used with such a system and, by extension, the cables that have those connectors on them.

The standard defines the electrical characteristics and timing of signals, the meaning of signals, and the physical size and pinout of connectors. The current version of the standard is TIA-232-F Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange, issued in 1997.

RS-485, or TIA/EIA-485, in contrast only specifies the electrical characteristics and not the data that is sent down the line. It doesn't specify any connectors to use, nor what format the data should take. For instance you can use RS-232 formatted packets, or you could use a MODBUS-RTU format that uses completely different packets. It only refers to the drivers and voltages used.

TIA-485-A, also known as ANSI/TIA/EIA-485, TIA/EIA-485, EIA-485 or RS-485, is a standard defining the electrical characteristics of drivers and receivers for use in balanced digital multipoint systems.

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