CLS200 Series User’s Guide
177
Proportional Control
A control using only the P (proportional) value of
PID control.
Pulse Input
Digital pulse signals from devices, such as
optical encoders.
R
Ramp
A programmed change in the temperature of a
setpoint system.
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.
Recipe
See Job.
Reflection Compensation Mode
A control feature that automatically corrects the
reading from a sensor.
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 control.
Solid State Relay (SSR)
A switching device with no moving parts that
completes or interrupts a circuit electrically.
Reset
Control action that automatically eliminates
offset or droop between setpoint and actual
process temperature. See also Integral Control.
Automatic Reset
The integral function of a PI or PID
temperature controller that adjusts the
process temperature to the setpoint after the
system stabilizes. The inverse of integral.
Resistance
Opposition to the flow of electric current,
measured in ohms.
Resistance Temperature Detector (RTD)
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.
Reverse Action
An output control action in which an increase in
the process variable causes a decrease in the
output. Heating applications usually use reverse
action.
RTD
See Resistance Temperature Detector.
S
Serial Communications
A method of transmitting information between
devices by sending all bits serially over a single
communication channel.
EIA/TIA-232
An Electronics Industries of America (EIA)
standard for interface between data terminal
equipment and data communications
equipment for serial binary data interchange.
This is usually for communications over a
short distance (50 feet [15 m] or less) and to
a single device.
EIA/TIA-485
An Electronics Industries of America (EIA)
standard for electrical characteristics of
generators and receivers for use in balanced
digital multipoint systems. This is usually used
to communicate with multiple devices over a
common cable or where distances over 50
feet (15 m) are required.
