Total isolation between RS-232 based systems and RS-422 is provided by
Telebyte's Model 265
RS-232 to RS-422 Optically
Isolated Interface Converter.
Unique circuitry allows the RS-422 port to withstand surges exceeding 10
kilovolts. A switch is included to reverse Pins 2 and 3 of the RS-232
connector to accommodate DTE or DCE ports. Data flow is displayed on TD
and RD LED indicators. The RS-232 input is a DB25 male connector. The
RS-422 interface is a five position terminal strip where one of the
terminals is an earth ground connection, used when the environment can
produce surges on the two twisted pairs of the RS-422 port. Since the
RS-422 circuitry is optically isolated a separate power supply (a wall
mounted transformer) is included for the RS-422 port. The power for the
RS-232 interface is derived from TD or any one of the control pins of
the interface, 4 (RTS), 5 (CTS), 6 (DSR), 8 (DCD), or 20 (DTR).
Full duplex transmission is provided up to 19.2 KBPS over a distance of