8
RS-232/485 CONVERTER
2. Introduction
2.1 Description
The RS-232/485 Converter (IC620A) is an ultra-
miniature interface converter. Requiring no
AC power or batteries for operation, the Converter
supports asynchronous communication up to
115.2 Kbps over one or two unconditioned
twisted pairs. Distances up to 15 miles (24 km)
are attainable at lower data rates (1.2 Kbps,
19 AWG twisted pair).
The Converter can handle up to 31 terminal drops
in a multipoint polling environment. For RS-485
applications that require hardware handshaking, the
Converter passes one control signal in each direction
(see the last bullet point in Section 2.2 for an
explanation). The Converter may be configured for
high or low impedance, and the carrier may be set to
“constantly on” or “controlled by RTS.” The unit can
operate with or without “echo.” RTS/CTS delay may
be set for “no delay” or “8 ms delay.”
There are three options for twisted-pair
connection: terminal blocks with strain relief, RJ-11,
or RJ-45. Silicon Avalanche Diodes provide 600 watts
per wire of protection against harmful data-line
transient surges.