Watlow PPC-2000 - Manual (Page 317)

PPC-2000 User’s Guide Glossary
Doc.# 30002-00 Rev 2.3 Watlow Anafaze 289
Protocol
A set of rules and formats governing a serial or
parallel communication channel.
Pulse Input
Digital pulse signals from devices, such as opti-
cal encoders.
R
Range
The area between two limits in which a quantity
or value is measured. It is usually described in
terms of lower and upper limits.
Register
A controller memory location. Registers are
either bit or word values.
Relay
A switching device.
Electromechanical Relay — A power switching
device that completes or interrupts a circuit by
physically moving electrical contacts into contact
with each other. Not recommended for PID con-
trol.
Solid State Relay (SSR) — A switching
device with no moving parts that com-
pletes or interrupts a circuit electrically.
Reset
Control action that automatically eliminates off-
set or droop between setpoint and actual process
temperature.
See also Integral.
Automatic Reset — The integral function of a
PI or PID temperature controller that adjusts the
process temperature to the setpoint after the sys-
tem stabilizes. The inverse of integral.
RTD (Resistance Temperature Detector/Device)
A sensor that uses the resistance temperature
characteristic to measure temperature. There are
two basic types of RTDs: the wire RTD, which is
usually made of platinum, and the thermistor
which is made of a semiconductor material. The
wire RTD is a positive temperature coefficient
sensor only, while the thermistor can have either
a negative or positive temperature coefficient.
S
Serial Communications
A method of transmitting information between
devices by sending all bits serially over a single
communication channel.
RS-232 — An Electronics Industries of America
(EIA) standard for interface between data termi-
nal equipment and data communications equip-
ment for serial binary data interchange. This is
usually for communications over a short distance
(50 feet or less) and to a single device.
RS-485 — An Electronics Industries of America
(EIA) standard for electrical characteristics of
generators and receivers for use in balanced digi-
tal multipoint systems. This is usually used to
communicate with multiple devices over a com-
mon cable or where distances over 50 feet are
required.
Setpoint (SP)
The desired value programmed into a controller.
For example, the temperature at which a system
is to be maintained.
Soft Bool
A generic Boolean variable which is stored in the
PPC-2000 database and is accessible by AnaWin
or a logic program. Values range from 1 to 0 (true
or false).
Soft Int
A generic integer variable which is stored in the
PPC-2000 database and is accessible by AnaWin
or a logic program. Values are –32,768 to 32,767.
Spread
In heat/cool applications, the +/- difference
between heat and cool. Also known as process
deadband.
Switch
Dip
A set of compact toggle switches used to config-
ure electronic hardware. The toggle switches are
housed in a Dual In-line Package.
Rotary
A switch with multiple dial-in settings used to
configure electronic hardware.