199 Publication 1763-UM001E-EN-P - June 2015
Appendix
E
Connecting to Networks via RS-232/RS-485
Interface
The following protocols are supported from the RS-232/485 communication
channel (Channel 0):
• DF1 Full Duplex
• DF1 half-duplex Master/Slave
• DF1 Radio Modem
• DH-485
• Modbus RTU Master/Slave
• ASCII
RS-232 Communication
Interface
The communications port on the MicroLogix 1100 utilizes a combined
RS-232/485 interface. RS-232 and RS-485 are Electronics Industries
Association (EIA) standards that specify the electrical and mechanical
characteristics for serial binary communication. They provide a variety of
system configuration possibilities. (RS-232 and RS-485 define electrical
connection characteristics, not protocols.)
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), but it is for point-to-point
connections only between two devices.
RS-485 Communication
Interface
The RS-485 interface supports connection of up to 32 devices in a multidrop
hard-wired configuration using DH-485, DF1-Half Duplex
(1)
, or Modbus
protocols. Also, the RS-485 interface supports connection in a multidrop
hard-wired configuration using ASCII protocols
(1)
.
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).
(1)
OS Series B FRN 4 or later.
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