Rockwell Automation 1762-Lxxxx MicroLogix 1200 Programmable Controllers - Manual (Page 131)

1 Publication 1762-UM001G-EN-P - March 2011
Appendix
E
Connect 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.