RS 485/232

The 232 and 485 numbers refer to the EIA/TIA 232 and EIA/TIA 485 standards which define the electrical characteristics of the 2 serial comm methods.

These standards do not address either the wiring or the connectors used for RS-232 or RS-485.

EIA 561 is supposed to be a standard for RS-232 on RJ-45 connectors, maybe for DB-9/25, but I've never seen a copy of it. When I first heard of EIA561, I asked engineers in 4 major companies that deal with devices with serial ports and none had heard of it. Furthermore, their customers haven't heard of EIA561. What drives vendor change is customer demand. If customers say, "I won't buy your widget unless the serial port complies with EIA 561" then vendors are likely to take notice.

Given that Windows PC's had a convention for wiring the DB-9 for the RS-232 on a COM port (back when you could buy a laptop with a serial port), but that serial ports are now disappearing, I suspect that it is too late to try to force vendor compliance for 232 or 485 pinouts. Had customers demanded EIA561 compliance 30 years ago, maybe. But now?

The bottom line in the real world is, the 232/485 serial connector does NOT define
- the electrical and physical transport layer 'behind' the connector
- the connector pinout
Nor does the electrical transmission system (232 or 485) define the connector used.

It's all vendor specific.