Отправлено albor 28 октября 2003 г. 15:24 В ответ на: Правильные названия сигналов RS-485 и RS-422 и соответствие между A/B и +/- ??? отправлено Vladimir Ljaschko 27 октября 2003 г. 14:43

Я в свое время пролюбился в коробочкой от MOXA ... Они мне заявили буквально следующее:
Dear Sir,

Thank you for using MOXA products. It's our pleasure to serve you.

Actually, the definition of "A" or "B" for RS-485 interface doesn't
have any standard in EIA regulation. According to our study and survey,
almost all of 4-wire RS-485 devices define its "+"="B" & "-"="B".
Hence, we follow this common usage to design our pinouts.

However, we still find some RS-485 devices define their own pinouts.
I think it's still OK. No matter "+"="B" or "A", you just need to
follow a simple regulation to connect your RS-485 device. That is,

DTE ---------- device
Tx+ ----------> Rx+
Tx- ----------> Rx+
Rx+ <---------- Tx+
Rx- <---------- Tx-
SGND ---------- SGND

Then, everything will be fine.