Rockwell Automation 150 USE MN/SMC DIALOG + CONTROLLER - Manual (Page 183)

Glossary-3
Port On a communication link, the logic circuitry or software at a station that determines
its communication parameters for a particular communication channel.
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).
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 instruc-
tions to implement specific functions such as I/O control, logic, timing, counting,
report generation, communication, arithmetic, and data file manipulation. A con-
troller consists of a central processor, input/output interface, and memory. A con-
troller is designed as an industrial control system.
Protocol A set of conventions governing the format and timing of data between communi-
cation devices.
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.
RS-232-C An EIA standard that specifies electrical, mechanical, and functional characteris-
tics 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.
RS-485 An EIA standard that specifies electrical characteristics of balanced-voltage digital
interface circuits in a multi-point link.
Scrolling The vertical movement of data on a display screen caused by the dropping of one
line of displayed data for each new line added at the opposite end.
Serial Pertaining to time-sequential transmission of, storage of, or logic operations on da-
ta, using the same facilities for successive parts.
Service Factor (S-F) When used on a motor nameplate, a number which indicates how much above the
nameplate rating a motor can be loaded without causing serious degradation (i.e.,
a motor with 1.15 S-F can produce 15% greater torque than one with 1.0 S-F) to
adjust measured loads in an attempt to compensate for conditions which are diffi-
cult to measure or define.
Silicon Controlled Rectifier A solid-state switch, sometimes referred to as a thyristor. The SCR has an anode,
(SCR) cathode and control element called the gate. The device provides controlled
rectification since it can be turned on at will. The SCR can rapidly switch large cur-
rents at high voltages. They are small in size and low in weight.
SLC

Controller An Allen-Bradley programmable controller with a name that includes the letters
SLC. See Programmable Controller.