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NETWORKING

7-59

System 2 Installation / Programming Manual

CHAPTER 7

NETWORKING

Introduction

Networking allows multiple System 2's to be linked together into one System. This option permits eight System

2 units, at two doors each, to be linked into a sixteen door System. Any System 2 in the network can be

designated as the “Master” with the remaining seven units designated as “Slaves”.

Once each unit is set up as a master or slave, all programming is done at the master and the programmed

information is then transferred to each slave. This distributed processing method insures rapid processing of

user information for fast door access and allows continued slave operation even if the communication link with

the master is broken.

RS485 Communications

The System 2 uses a high-speed RS485 buss for communications between the master and slaves. This buss

uses a shielded, twisted pair of wires which can be up to 4000 feet in length. The RS485 buss allows

System 2's and future devices to be connected anywhere on the pair of wires for further expansion.

The master polls one slave, in turn, every second until all the slaves are polled. This process then repeats. The

master continuously polls one slave at a time and waits for a response. This poll - response method is used to

pass new information to a slave or to get information stored in the slave’s event buffer.

Linking Multiple System 2's Together

System 2 can support a total of eight units linked together on the RS485 communications buss. One of the

units must be designated as a “Master”. The Network Option is used to configure each unit as a master or a

slave. Once configured, the master is responsible for the programming. This is accomplished through the use

of the built-in LCD and keypad, a Video Display Terminal (VDT) or a personal computer (PC).

A two conductor, 22 gauge, twisted pair, shielded cable is needed to link the master to any of the additional

units (slaves) on the System. The System utilizes a “multi-drop/daisy-chain” wiring configuration, as opposed

to a “home-run” from each slave to the master. This allows a single cable to be installed throughout the

building and tapped into with a slave at any point.

IMPORTANT: The first and last System 2 board must have a 120ohm resistor installed across Terminals

#14 & #15. Failure to install these resistors will result in erratic operation of the entire System.

Refer to Figure 34.

1 2 ... 60 61 62 63 64 65 66 67 68 69 70 ... 335 336

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