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Merrydown Controlware - Industrial automation terms
Category: Electronics and Engineering > Industrial Automation
Date & country: 13/11/2007, UK
Words: 25


Analyser
A special class of instrument that provides component based data rather than basic physical data. Examples are gas chromatographs and near infra-red analysers.

BRAIN
This is the name of the protocol used by Yokogawa for communications with their smart instrumentation. It is similar in principle to the HART system but is a slightly different implementation.

Burner Management System
A special application of a control system to the task of safe startup and shutdown of a combustion process. BMSs are often implemented on special high integrity control systems (such as fail safe controllers) because of the safety requirement in burning fuels.

Cascade Control
A control technique that involves one controller manipulating a second controllers setpoint. A common example is a tank level controller manipulating the setpoint of an inlet flow controller.

Combustion Control System
A special application of a control system to the task of the control of a combustion process (compare with BMS).

Controller
A device that minimises the difference between a desired value (often called the setpoint) and a measured value (often called the process variable) by manipulation of an output.

Cross-Limiting Strategy
A control system technique where there are two or more control outputs to manipulate but it is required to move one of them first on increasing demand and the other one first on reducing demand.

Database
A collection of organised data that can be searched, re-arranged and processed to enhance its value. Database is a bad description in reality. It should be called an information-base since data is just a collection of numbers, letters, pictures etc where as information is a usable and valueable collection.

Direct Digital Control [DDC]
The use of a single processing entity to generate outputs for a control system.

Distributed Control System [DCS]
A control system in which the processing power is distributed amongst several processors.

Dynamic Matrix Controller [DMC]
An advanced control technique that uses as a basis a matrix relating input movements to output movements.

Expert System
An expert system is a procedure consisting of a set of heuristic type rules instead of process models or other mathematical analysis. In its simplest implementation an expert system can be thought of as a set of 'if condition X then do Y' type statements rather than Y=fn(X) type statements.

Feedback Control
A control strategy where the controller uses a process variable that is affected by the control output. Feedback control has nothing to do with the physical location of the measurement point and the control point in the process, often the measurement point is after the control point but not always.

Feedforward Control
A control strategy where the controller uses a process variable that represents what disturbances will affect the process. An example of feedforward control is to measure the inlet flow to a tank and manipulate the outlet flow of the tank in order to control the tank level.

Fieldbus
Fieldbus is a method of connecting field instrumentation using a communications network linking the field instruments rather than connecting each field instrument individually to the control system.

Fuzzy Logic
Fuzzy logic was formalised by Lofty Zadeh to overcome the inadequacies of conventional logic when analysing real world systems.

Human-Computer Interface [HCI]
The parts of a computer system that interacts with a human. The HCI includes all the hardware (VDUs, keyboards, mice, trackerballs, annunciators etc) and the software with an necessary configuration needed to drive them.

Instrument
A physical device that either measures a process condition or manipulates a process variable. Examples are flow transmitters, level gauges, control valves, speed regulators.

Integrating Process
An integrating process is one where an error in the amount of control action will result in a continually rising or falling process variable.

Man-Machine Interface
Replaced by the term Human-Computer Interface.

Positioner
A field based device that takes a signal from a control system and ensures that the control device is at the setting required by the control system.

Regulatory Process
An regulatory process is one where an error in the amount of control action will result in a fixed offset between the setpoint value and the process variable.

Smart Instrument
Smart instrumentation is any field device that, in addition to transmitting the measurement variable or receiving the control variable, also transmits other process information and/or diagnostic information about the device.

Split Range Control
A control technique where the output of a controller is divided into 2 or more signals that are applied to different control devices.

Supervisory Process Control [SPC]
The use of a single processing entity to generate setpoints for a control system.