e SLC 5/03, SLC 5/04, and SLC 5/05 processors have a serial port which is
configurable for RS-232 compatible serial communication. Use the serial port to
connect to devices that:
communicate using DF1 protocol, such as modems, communication modules,
programming workstations, or other Encompass partner devices.
communicate using DH-485 protocol.
communicate using Modbus RTU Master as a new communication protocol to
third-party Modbus RTU Slave devices.
send and receive ASCII characters, such as ASCII terminals, bar code readers,
and printers.
When configured for system mode, the serial port supports DF1 protocol. Use
system mode to communicate with other devices on the serial link. You can select
the following DF1 modes:
DF1 full-duplex: provides communication between an SLC 500 controller and other
DF1 compatible devices. In point-to-point mode, the SLC 500 controller uses DF1
full-duplex protocol.
DF1 half-duplex master: polls and transmits messages between the master and
each remote node. In master mode, the SLC 500 controller uses DF1 half-duplex
polled protocol.
DF1 half-duplex slave: uses the controller as a slave station in a master/slave serial
network. In slave mode, the SLC 500 controller uses DF1 half-duplex protocol.
DF1 radio modem: a hybrid between DF1 full-duplex and DF1 half-duplex, this
protocol is optimized for use with radio modem networks.
In system mode, the serial port also supports supervisory control and data acquisition
(SCADA) applications. SCADA systems allow you to monitor and control remote
functions and processes using serial communication links between master and
slave locations.
When configured for user mode, the serial port supports ASCII devices. Use the
SLC 500 ASCII instructions

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