Glossary
A-18 Appendix 6 535 User's Manual
control action, proportional plus
integral (PI): A control algorithm
that provides proportional control
with the addition of integral action
to compensate for offsets between
setpoint and process variable.
control action, proportional plus
integral plus derivative (PID): A
control algorithm that provides
proportional control with both
integral and derivative action.
control, adaptive: (see adaptive
control)
control algorithm: A
mathematical representation of the
control action to be performed.
control, cascade: (see cascade
control)
control output: The end product
which is at some desired value
that is the result of having been
processed or manipulated.
control mode, automatic: A user
selected method of operation
where the controller determines
the control output.
control mode, manual: A user
selected method of operation
where the operator determines the
control output.
control parameters: User defined
values that specify how the
process is to be controlled.
controlled variable: A process
variable which is to be controlled
at some desired value by means
of manipulating another process
variable.
CRC (cyclic redundancy check):
An error checking technique in
which a checking number is
generated by taking the remainder
after dividing all the bits in a block
DIN: Deutsche Industrial Norms, a
German agency that sets standard
for engineering units and
dimensions.
display, 1st: The top, largest
display of controller face that is
used to display the process
variable value.
display, 2nd: The middle display
of the controller face used to
indicate: in OPERATION Mode -
the setpoint, deviation or output; in
TUNING or SET UP Mode - the
parameter or parameter menu.
display, 3rd: The bottom display
of the controller face that is used
to indicate: in OPERATION Mode -
the setpoint, deviation or output; in
TUNING or SET UP Mode - the
parameter or parameter menu.
disturbance: An undesired
change that takes place in a
process that tends to affect
adversely the value of a controlled
variable.
duty cycle: Percentage of “load
ON time” relative to total cycle
time.
earth ground: A terminal used on
the 535 to ensure, by means of a
special connection, the grounding
(earthing) of part of the controller.
engineering unit: Terms of data
measurement such as degrees
Celsius, pounds, grams, etc.
feedback: Process signal used in
control as a measure of response
to control action; the part of a
closed-loop system which
automatically brings back
information about the condition
under control.
(in serial form) by a predetermined
binary number.
CSA: Acronym for Canadian
Standards Association.
cycle time: The time necessary to
complete a full ON-through-OFF
period in a time proportioning
control system.
damping: The decrease in
amplitude of an oscillation due to
the dissipation of energy.
damped, 1/4 amplitude: The loss
of one-quarter of the amount of
amplitude with every oscillation.
dead band: A temperature band
between heating and cooling
functions; the range through which
an input can be varied without
initiating observable change in
output.
dead time: The interval of time
between initiation of an input
change or stimulus and the start of
the resulting observable response.
default settings: Parameters
selections that have been made at
the factory.
derivative: Anticipatory action that
senses the rate of change of
temperature, and compensates to
minimize overshoot and
undershoot. Also “rate.”
derivative action: (See control
action, derivative)
deviation: The difference between
the value of the controlled variable
and the value at which it is being
controlled.
digital input: Used in this manual
to indicate the status of a dry
contact; also called “gate”.
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