D8 Series User’s Guide
165
Process Hysteresis
— In heat/cool
applications, the +/- difference between heat
and cool. Also known as process deadband
I
Input
Analog Input
— An input that accepts
process variable information.
Digital Input
— An input that accepts on and
off signals.
Input Scaling
The converting of input signals to the
engineering units of the process variable.
Input Type
The signal type that is connected to an input,
such as thermocouple, RTD or process.
Instance
An object that is an occurance of a class.
Each instance of a DeviceNet™ object can
have unique values for its attributes and can
be examined or changed using the instance
services. Class services are used to examine
and change class attributes, which affect
all instances. Instance services are used to
examine and change instance attributes which
affect only that particular instance.
Integral Control (I)
Control action that automatically eliminates
offset, or droop, between set point and actual
process temperature.
J
Job
A set of operating conditions for a process
that can be stored and recalled in a controller’s
memory. Also called a
recipe
.
Junction
The point where two dissimilar metal
conductors join to form a thermocouple.
K
Keypad Lock
A feature that prevents operation of the keypad
by unauthorized people.
L
Lag
The delay between the output of a signal and
the response of the instrument to which the
signal is sent.
Linearity
The deviation in response from an expected or
theoretical straight line value for instruments and
transducers. Also called
linearity error
.
Load
The electrical demand of a process, expressed
in power (Watts), current (Amps) or resistance
(Ohms). The item or substance that is to be
heated or cooled.
Low Deviation Alarm
Warns that the process has dropped more than
a certain amount below set point. It can be used
as either an alarm or control function.
Low Alarm
A signal that is associated with a set minimum
value that can be used as either an alarm or
boost control function.
M
Manual Mode
A selectable mode that has no automatic
control aspects. The operator sets output levels.
Manual Reset
A parameter that allows the user to eliminate
offset or droop between set point and actual
process temperature. See also Integral.
Milliampere (mA)
One thousandth of an ampere.