[Elecraft] What's wrong with Serial

[Mike S]

At 10:53 PM 6/19/2006, Ron D'Eau Claire wrote...
>years I've worked with RS232 interfaces. People jump to a very wrong
>assumption that RS232 defines the connections at a given cable connector...
>RS232 is a signaling protocol, not a cable pinout scheme. 

RS-232 and it's successors are interface standards, and as such define electrical signal, logical function and physical connection standards. In fact, the one thing it doesn't define is an upper layer signaling protocol - which is why you must also know whether you're dealing with sync/async and the specific serial encoding to be used. It predates the modern ISO layered architecture, but would fit best as a Physical Layer (Layer 1) standard.

RS-232 has always specified a cable pinout; originally on an unspecified 25 pin connector. Later, in RS-232C, it specified the common Cannon DB-25 connector.

RS-232 as such is obsolete, and in informal use is normally taken to refer to the current standard, ANSI/EIA/TIA-723-1998 "High Speed 232 Type DTE/DCE Interface," which replaced EIA/TIA-232. The standard says the DE-9 interface shall be referred to as "ANSI/EIA/TIA-723 Alt B." In addition to the regular DB-25, there is also a 26 pin "Alt A."