Chapter 1 - Overview; Description; Electrical Specifications; Virtual Pin Assignments And Theory Of Operation - TC Communications TC1720 User Manual

Rs-422/rs-449 async/sync fiber optic modem (with optional dual optics)

Hide thumbs

Table Of Contents

Table of Contents

Description

The TC1720 RS-422/RS-449 is an economical and dependable fiber optic modem which links data

communication equipment requiring an RS-422A interface. It supports Asynchronous data speeds of up to

10 Mbps & Synchronous data speeds of up to 5 Mbps and is equipped with a male DB37 connector. A four-

position DIP switch provides for Remote & Local Loopback functions, Slave Clock operation & Alarm

disabling capability.

It is available in either rack mount or stand alone versions; the rack mount version can be converted to the

stand alone version with the addition of a sheet metal box. The TC1720 can communicate at distances up

to 4 km using Multimode optics and up to 80 km using Single Mode optics. Fiber optic connectors can be

either ST or FC type. TC1720's design utilizes advanced FPGA (Field Programmable Gate Array) technology

to increase reliability and flexibility.

The TC1720 has multiple LED indicators to ease installation and troubleshooting. These LEDs indicate status

for power, operating voltage, alarm, transmit & receive electrical signals, optical signal and more.

Electrical Specifications

Interface:

RS-422/RS-449 Async/Sync

Data Rates:

Async

Sync

Connector:

DB37 Male (DCE/DTE switch selectable)

Virtual Pin Assignments & Theory of Operation

Virtual Connection

(Connect DTE to DCE device)

TC1720

DCE

SD,SD

4,22

RD,RD

6,24

from DTE

device

TT,TT

17,35

RT,RT

8,26

ST,ST

5,23

FRAME GND

SIGNAL GND

Figure 1. Connecting a DTE to DCE Device

Logic Diagram

The TC1720 latches onto the RS-422/RS-449 data by the received clock signal (from user's equipment or

the internal clock generator from the TC1720) to produce an encoded optic signal (with an embedded clock).

The composite optic signal is then transmitted by the optic transmitter through the optic cable to a remote

TC1720's optic receiver. The received optic signal is processed and decoded to separate data and clock from

the composite optic signal and then transmitted out to a remote device.