Rockwell Automation 1747-L40 SLC 500 Fixed Hardware Style - Manual (Page 124)

C
Appendix
C–1
RS-232 Communication Interface
This appendix provides an overview of the RS–232 communication interface.
This appendix also provides information on the following:
•
RS–232 and SCADA applications
•
RS–232 communication interface overview
•
SLC 500 devices that support RS–232 communication
•
wiring connectors for RS–232 communication
RS–232 is a communication interface included under SCADA (Supervisory
Control and Data Acquisition) applications. SCADA is a term that refers to
control applications that require communication over long distances. For
more information about the use of Allen–Bradley equipment in SCADA
applications, refer to the Allen–Bradley SCADA Applications Guide,
Publication Number ICCG–11.6.
RS–232 is an Electronics Industries Association (EIA) standard that specifies
the electrical, mechanical, and functional characteristics for serial binary
communication. It provides you with a variety of system configuration
possibilities that differ from those offered by DH–485.
One of the biggest benefits of RS–232 communication is that it lets you
integrate telephone and radio modems into your control system. The
distance over which you are able to communicate with certain system devices
is virtually limitless.
The SLC and PLC products detailed in this appendix that communicate over
the RS–232 communication interface also use the DF1 serial communication
protocol. DF1 protocol delimits messages, controls message flow, detects
and signals errors, and retries after errors are detected.
RS-232 and SCADA
Applications
RS-232 Communication
Interface Overview