8
RS-485 Repeater and RS-485 Repeater (Opto-Isolated)
The RS-485 Repeaters extend your
RS-485 communications beyond the
4000-foot limit. Even located 5000
feet from your master device, they’ll
take your RS-485 communications
signals and shoot them out another
4000 feet.
And they let you add more devices
to your network—up to 32 more
unit loads per Repeater. The RS-
485 Repeaters are perfect for
connecting multiple RS-485
segments located in different
rooms, on different floors, or in
different buildings.
They support either 2- or 4-wire
applications, in full- or half-duplex
operation. Plus they come with a
4-screw terminal-block, RJ-45
connectors, and an edge card
connector, so they fit right in with
any RS-485 wiring scheme.
2.1 Optical Isolation (IC158A only)
The opto-isolating model protects
one segment of your extended
network from problems that arise
on the other. Inside the Repeater,
optical-isolation circuitry converts
electrical signals to light and back
again, to keep signal noise and
ground loops from crossing
between segments of your RS-485
installation. That means the
electrical noise from your factory
floor won’t affect your office
communications, and the difference
in ground potential between
buildings won’t damage your
sensitive equipment.
2.2 Indicators and Connectors
Three LEDs are visible through the
Repeater's translucent front panel:
one Power LED and two Carrier
Detect (CD) LEDs. The power LED
lets you know the Repeater is on,
while the CD LEDs indicate when a
transmitter is enabled on the RS-
485 line.
Five connectors are accessible
through the Repeater back panel:
the Power connector, two RJ-45
connectors, and two 4-screw
terminal blocks. The Port A
terminal block and the RJ-45
connector are wired in parallel to
each other. Thus the A and B ports
of the repeater can be accessed
through either a terminal-block
connector or an RJ-45 connector.
(See Figs. 3-1 and 3-2 for the
position of these components on
the Repeater circuit board.)
Chapter 3.0
covers installation of
the RS-485 Repeaters in your
setup.
NOTE:
The RS-485 Repeater has
no collision detection. It is up to
the addressable devices on the
RS-485 network to ensure that only
one transmitter is enabled at any
one time.
2.0 Introduction