Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers - Manual (Page 338)

Preface MicroLogix 1000 Programmable Controllers User Manual
D–10
Radio Modems
Radio modems may be implemented in a point-to-point topology supporting either
half-duplex or full-duplex communications, or in a point-to-multipoint topology
supporting half-duplex communications between three or more modems. In the
point-to-point topology using full-duplex radio modems, configure the MicroLogix
1000 controllers for DF1 full-duplex protocol (as long as the modems used do not
require DTR or RTS to be high in order to operate). In the point-to-point topology
using half-duplex radio modems, or point-to-multipoint topology using half-duplex
radio modems, configure the MicroLogix 1000 controllers for DF1 half-duplex
slave protocol. If these radio modems require RTS/CTS handshaking, configure the
control line parameter to “Half-Duplex Modem”.
Line Drivers
Line drivers, also called short-haul “modems”, do not actually modulate the serial
data, but rather condition the electrical signals to operate reliably over long
transmission distances (up to several miles). Allen-Bradley’s AIC+ Advanced
Interface Converter is a line driver that converts an RS-232 electrical signal into an
RS-485 electrical signal, increasing the signal transmission distance from 50 to 4000
feet. In a point-to-point line driver topology, configure the MicroLogix 1000
controller for DF1 full-duplex protocol (as long as the line drivers do not require
DTR or RTS to be high in order to operate). In a point-to-multipoint line driver
topology, configure the MicroLgoix 1000 controllers for DF1 half-duplex slave
protocol. If these line drivers require RTS/CTS handshaking, configure the control
line parameter to “Half-Duplex Modem”.