Emerson Fisher FIELDVUE DVC6000f, Instruction Manual

Page: 369 / 384

Glossary
December 2009 Glossary-1
Glossary
Algorithm
A set of logical steps to solve a problem or
accomplish a task. A computer program contains
one or more algorithms.
Alphanumeric
Consisting of letters and numbers.
ANSI (acronym)
The acronym ANSI stands for the American
National Standards Institute
ANSI Class
Valve pressure/temperature rating.
Bench Set
Pressure, supplied to an actuator, required to
drive the actuator through rated valve travel.
Expressed in pounds per square inch.
Byte
A unit of binary digits (bits). A byte consists of
eight bits.
Configuration
Stored instructions and operating parameters for
a FIELDVUE Instrument.
Control Loop
An arrangement of physical and electronic
components for process control. The electronic
components of the loop continuously measure
one or more aspects of the process, then alter
those aspects as necessary to achieve a desired
process condition. A simple control loop
measures only one variable. More sophisticated
control loops measure many variables and
maintain specified relationships among those
variables.
Controller
A device that operates automatically to regulate a
controlled variable.
Crossover Point
The mid-point of the stroking range of a
sliding-stem actuator. A visual indication of the
crossover point is found when the slot in the
instrument feedback arm forms a 90-degree
angle with the valve stem.
Deadband
Region around a reference point that must be
exceeded before a new event occurs.
Deviation
Usually, the difference between set point and
process variable. More generally, any departure
from a desired or expected value or pattern.
Device ID
Unique identifier embedded in the instrument at
the factory.
Drive Signal
The signal to the I/P converter from the printed
wiring board. It is the percentage of the total
microprocessor effort needed to drive the valve
fully open. In most applications, drive signal
ranges from 55% to 75%.
Feedback Arm
The mechanical connection between the valve
stem linkage and the FIELDVUE Instrument
travel sensor.
Feedback Signal
Indicates to the instrument the actual position of
the valve. The travel sensor provides the
feedback signal to the instrument printed wiring
board assembly. A mechanical linkage connects
the travel sensor to the valve stem or shaft.
G
Glossary