Rockwell Automation 150 MNL/SMC DIALOG+/APP-PROD GUIDE - Manual (Page 198)

Glossary-11
PLC
®
Controller 1. An Allen-Bradley programmable controller.
2. An Allen-Bradley programmable controller with a name that includes th
letters PLC. Se Programmable Controller.
Plugging Plugging refers to a type of motor braking provided by reversing either line voltage
polarity or phase sequence so that the motor develops a counter-torque which
exerts a retarding force to brake the motor.
Port On a communication link, the logic circuitry or software at a station that determines
its communication parameters for a particular communication channel.
Power Work done per unit of time. Measured in horsepower or watts: 1 HP = 33,000 ft.-
lb./min. = 746 watts.
Power Factor A measurement of the time phase difference between the voltage and current in an
AC circuit. It is represented by the cosine of the angle of this phase difference.
Power factor is the ratio of Real Power (kW) to total kVA or the ratio of actual
power (W) to apparent power (volt-amperes).
Power Supply A device that converts available power to a form that a system can use ó usually
converts AC power to DC power.
Preset Speed Preset speed refers to one or more fixed speeds at which the drive will operate.
Programmable Controller A solid-state system that has a user-programmable memory for storage of
instructions to implement specific functions such as I/O control, logic, timing,
counting, report generation, communication, arithmetic, and data file
manipulation. A controller consists of a central processor, input/output interface,
and memory. A controller is designed as an industrial control system.
Protocol A set of conventions governing the format and timing of data between
communication devices.
Pulse A momentary sharp change in voltage, current, or light from its quiescent
condition.
Remote I/O I/O connected to a processor across a serial link. With a serial link, remote I/O can
be located long distances from the processor.
Reversing Changing the direction of rotation of the motor armature or rotor. A DC motor is
reversed by changing the polarity of the field or the armature, but not both. An AC
motor is reversed by reversing the connections of one leg on the three phase power
line or by reversing the leads on a single phase power line.
RS-232-C An EIA standard that specifies electrical, mechanical, and functional
characteristics for serial binary communication circuits in a point-to-point link.
RS-422 An EIA standard that specifies electrical characteristics of balanced-voltage digital
interface circuits in a point-to-point link.