With proper grounding, surge management, and optical/galvanic isolation any RS-422
or RS-485 data comm link can last "forever". Contrary to the popular fatalism,
port failures are not an inevitable part of data comm. This application
note discusses the creation of such robust, long term links. It also explains
the popular misconception that RS-422 is a purely "4-wire" circuit and RS-485
a purely "2-wire" circuit - which overlooks the critical signal return. No free
lunch here!
