Rockwell Automation 1400-SP PowerMonitor Software - Manual (Page 69)

B Appendix
B–1
Communications Application Note
This document gives a brief overview and comparison of the RS–232C and
RS–485 communication standards, along with a list of factors to consider
when deciding which of the standards is best suited to your metering
application.
Also included is an application note covering using modems with the
Powermonitor Software.
!
ATTENTION: Special high level isolation is required between
units when the possibility of high ground potential differences
exist. This may occur when separate grounds are used, or when
communicating to a unit off of the power ground matt. Failure to
do so can lead to personal injury or death, property damage, or
economic loss.
RS–232C is an electrical standard used to provide serial communications
between electronic devices.
IBM PC–AT/286/386 or compatible computers have the ability to
communicate via RS–232C when a serial communications card or “PORT”
is installed into one of its internal PC expansion slots. The connector for this
port is usually located at the back of the computer.
When two electronic devices are equipped with an RS–232C port, they can
be connected together via an RS–232C cable over which information is
transferred. The minimum cable requirements for RS–232C is a 22 AWG
shielded three conductor cable.
Normally, the maximum length of cable used to connect two electronic
devices via RS–232C is 50 feet.
Introduction
What Is RS–232C?