User's Manual

Page 26

Extending the RS-485 Specification

Some systems require longer distances or higher numbers of nodes than supported

by RS-485. Repeaters are commonly used to overcome these barriers. An RS-485

repeater can be placed in a system to divide the load into multiple segments.

Each “refreshed” signal is capable of driving another 4000 feet (1200 meters) of

cable and an additional 31 RS-485 unit loads. Using an Ethernet network with

switches can also solve this problem. The Veri-Series units represent a single unit

load to the transmission line.

Figure 14: Wiring Diagram for RS-232/RS-485 Converter

Wiegand Ground

Wiegand Out Data1

Wiegand Out Data0

Power

Supply

+12 VDC

Ground

Pigtail

Door

Controller

Data 0

Data 1

Common

Earth

Ground

Computer

RS-232

TD(A)

TD(B)

RD(A)

RD(B)

+12VDC

GND

RS-485 (-)

RS-485 (+)

Connect to

Earth

Ground

Twisted Pair.

Use Cat5 rated cable

Figure 13: Network Configuration