1 Publication 1762-UM001D-EN-P - March 2004
Appendix
E
Connecting to Networks via RS-232 Interface
The following protocols are supported from the RS-232
communication channel:
• DF1 Full Duplex
• DF1 Half Duplex
• DH-485
• Modbus
• ASCII
RS-232 Communication
Interface
The communications port on the MicroLogix 1200 utilizes an RS-232
interface. RS-232 is an Electronics Industries Association (EIA)
standard that specifies the electrical and mechanical characteristics for
serial binary communication. It provides you with a variety of system
configuration possibilities. (RS-232 is a definition of electrical
characteristics; it is not a protocol.)
One of the biggest benefits of an RS-232 interface is that it lets you
integrate telephone and radio modems into your control system (using
the appropriate DF1 protocol only, not DH-485 protocol).
DF1 Full-Duplex Protocol
DF1 Full-Duplex protocol provides a point-to-point connection
between two devices. DF1 Full-Duplex protocol combines data
transparency (American National Standards Institute ANSI - X3.28-1976
specification subcategory D1) and 2-way simultaneous transmission
with embedded responses (subcategory F1).
The MicroLogix 1200 controllers support the DF1 Full-Duplex protocol
via RS-232 connection to external devices, such as computers, or other
controllers that support DF1 Full-Duplex.
DF1 is an open protocol. Refer to DF1 Protocol and Command Set
Reference Manual, publication 1770-6.5.16, for more information.
DF1 Full-Duplex protocol (also referred to as DF1 point-to-point
protocol) is useful where RS-232 point-to-point communication is
required. DF1 protocol controls message flow, detects and signals
errors, and retries if errors are detected.
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