Rockwell Automation DAG6.5.8 APPLICATION GUIDE SCADA SYSTEM - Manual (Page 210)

Publication AG-UM008C-EN-P - February 2005
6-6 Configuring MicroLogix 1000 Controllers
Dial-up Phone Modems
Dial-up phone line modems support point-to-point full-duplex
communications. Normally, a MicroLogix controller is on the receiving
end of the dial-up connection, and is configured for DF1 full-duplex
protocol. The modem connected to the MicroLogix controller must
support auto-answer and must not require any modem handshaking
signals from the MicroLogix (i.e. DTR or RTS) in order to operate. The
MicroLogix has no means to cause its modem to initiate or disconnect
a phone call, so this must be done from the site of the remote modem.
Leased-Line Modems
Leased-line modems are used with dedicated phone lines that are
typically leased from the local phone company. The dedicated lines
may be point-to-point topology supporting full-duplex
communications between two modems or in a point-to-multipoint
topology supporting half-duplex communications between three or
more modems. In the point-to-point topology, configure the
MicroLogix 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-multipoint topology, configure the MicroLogix controllers for
DF1 half-duplex slave protocol with the control parameter set to
Half-Duplex Modem.
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 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
controllers for DF1 half-duplex slave protocol. If these radio modems
require RTS/CTS handshaking, configure the control line parameter to
Half-Duplex Modem.