Intelligent RS-485 and RS-422 Adaptors
2
RS-485 and RS-422 Cabling
RS-422 and RS-485 are specifications for multi-drop serial digital
communications over long distances with high noise immunity.
In ASP products, RS-422 is a four-wire connection (with one twisted-
pair used for transmission and one twisted-pair used for reception), and
RS-485 is a two-wire connection (with transmission and reception
taking place alternately over a single twisted-pair).
ASP RS-422 products
ASP RS-485 products
ASPNet Terminals
ClassNet Terminal
ASPNet Access Controller
ZipNet Terminal
Networked Portable BCR
WandNet
ASP RS-422 and RS-485 networks must be wired using a single run of
shielded twisted-pair cable, daisy chained to each unit. The cable must
be looped to each unit in one continuous run - there must be no "T" or
"Y" connections in the cable. Cable joins are acceptable only at the
actual connectors at each unit (see the diagram below).
Note that although
this diagram shows
ClassNet or ZipNet
units, the way the
cable is run is
applicable to
all
ASP networked
units.
In a typical
installation, one
end of the cable is
connected to the
Intelligent RS-485
or RS-422
Adaptors at the
controlling computer (which plugs into one of the computer's serial
ports). The cable is then run to each networked unit in turn, with no
branches or junctions.
