Industrial Automation and Control Technology

This set covers the fundamental definitions of industrial automation, power elements, control system types, Boolean logic operations, and PLC architecture and programming.

Automation

The technology by which a process or procedure is accomplished without human assistance.

Power

A basic element of an automated system used to drive the process itself, load/unload work units, transport operations, and operate the controller unit.

Electricity

The principal power source for automation because it is widely available, can be converted to other forms (mechanical, thermal, light), and used for signal transmission.

Program of Instructions

A set of commands that specify the sequence of steps in the work cycle and the specific details of each step.

Control System

A device or collection of components connected in a manner as to command, direct, or regulate itself or another system.

Closed-loop (feedback) control system

A system in which the output variable is compared with an input parameter, and the difference is used to drive the output into agreement with the input.

Open-loop control system

A system that operates without a feedback loop; it is simpler and less expensive but carries a risk that the actuator will not have the intended effect.

Boolean Algebra

A mathematical system used to represent and analyze logical relationships using only two values: $1$ (TRUE/ON) and $0$ (FALSE/OFF).

AND Operation (Conjunction)

A logic operation where the output is $1$ only if all inputs are $1$; equivalent to contacts in series in a PLC.

OR Operation (Disjunction)

A logic operation where the output is $1$ if at least one input is $1$; equivalent to contacts in parallel in a PLC.

NOT Operation (Inversion)

A logic operation where the output is the opposite of the input; represented in a PLC by a Normally Closed (NC) contact.

Programmable Logic Controller (PLC)

A microcomputer-based controller that uses stored instructions in programmable memory to implement logic, sequencing, timing, and counting functions.

PLC Processor

The component that executes logic and sequencing functions by operating on PLC inputs to determine appropriate output signals.

PLC Power Supply

A component that converts $120\,\text{V}$ (ac) to dc voltages of $\pm 5\,\text{V}$ compatible with process equipment.

Scan Time

The time required for a PLC to perform the input scan, program scan, and output scan, varying between $1$ and $25\,\text{msec}$.

Ladder Logic Diagrams

The most widely used graphical PLC programming language, featuring logic elements displayed along horizontal rungs connected to vertical rails.

Contacts

Logical inputs in ladder logic, such as limit switches or photo-detectors, which can be normally open (NO) or normally closed (NC).

Loads

The outputs in ladder logic, examples of which include motors, lights, alarms, and solenoids.