Title: Articles of Implementation
Course: 2016FA-MCO-110-401 > Section: Module 5: Control Theory

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Articles of Implementation

DDC

Direct Digital Control (DDC) is a system in which electronic signals are received from sensors, the signals are then converted into numbers, mathematical operations are performed inside a digital computer, and the computer then outputs data that is converted into either a voltage or a pneumatic signal that directly manipulates the actuator [20]. Increased energy efficiency, operation efficiency, and an overall improvement in effectiveness are the main reasons DDC is found useful. Fire control systems, lighting control systems, access control systems, and maintenance management systems are just a few systems with which DDC systems can easily integrate [21].

PLCs

Programmable logic controllers (PLCs) are computer based controllers that can have multiple inputs and outputs and can be field programmable. They can be connected to many different analog and digital devices. A PLC could be used in many industrial and mission critical applications and typically control electromechanical processes. PLCs are common in SCADA systems. PLCs are made to be durable and can withstand conditions that are hot or cold, noisy, and have vibrations.

DCS

A distributed control system, or DCS, is a logic unit (or brain) of a control system, it networks local controllers together. It is used often in automating a manufacturing process. DCSs are connected to sensors and actuators and can be used to control the flow of material using the set point. The measured variable reaches a certain point and the controller has a valve close or an actuator to act in order to reach the desired setpoint.

Embedded Controllers

In a computer, embedded controllers (EC) are a type of microcontroller that allows for handling multiple tasks by allowing certain tasks to be handled without having to go through the operating system. In automation however, an embedded control system where the I/O [1]system has its own processor incorporated into it [22].

VFDs

A variable frequency drive (VFD) is a device that includes a circuit that allows an AC motor to run at different speeds. VFDs may share some basic control architecture with PLCs, but do not have the same extensive control capabilities that a PLC does. A VFD is typically responsible only for a single actuator.

Sensors

A sensor is a device that detects changes or events in its environment. Sensors can be used to measure a plethora of things. Examples of things sensors measure include temperature, humidity, weight, or acceleration. Industrial sensors measure, record, or calculate outputs. These outputs can fall into the following categories.

Environment – The industrial setting requires many sensors that fall into the category of environment. This is where the weight, temperature and humidity sensors fall. There is a vast assortment of sensors that fit into this category.

Level – For instance to prevent over or under fill the level of water in a tank can be measured using a sensor.

Light – Sensors called photoelectric sensors are capable of telling if light is present or not. This can be used to detect holes in textiles or other materials, as part of a process in guiding the movement of a robot, or in combination with other components as a part of a scanner.

Position – Sensors make it possible to judge where something is; there are many position encoders available to sense position.

Proximity – It is possible to use a sensor to judge how for to move something in a factory or for safety purposes to keep something from happening if an operator is too close [23].

Actuators

An actuator is a device used in a process control system to translate the control signal into an action. Actuators can be energized by electric, hydraulic, or pneumatic power and are often used on motors, cylinders, and solenoids to open and close valves [3].

Smart Devices

The IT Law Wiki defines a smart device as, “a device that is digital, active, computer networked, is user reconfigurable, and that can operate to some extent autonomously [24]. “

[1] I/O – Stands for Input/Output; this represents signal or data transfer [38]. (For instance, signals received would be called inputs and signals sent would be called outputs.)

Objectives met:
- C5
- 5.6