PLC Quiz

Programmable Logic Controllers (PLCs)

• Dick Morley is considered the father of PLC.

Definition and Purpose of PLC

• A programmable logic controller (PLC) is a digital computer used to control and monitor industrial processes and machinery.
• The purpose of a PLC is to control and automate industrial processes, replacing relay-based circuitry.

Characteristics of PLC

• PLCs are programmable, flexible, and modular.
• They are resistant to noise, vibration, and temperature changes.

Dick Morley's Invention

• Dick Morley invented the first PLC, the Modicon 084, in 1969.

Disadvantages of Relay-Based Circuitry

• A disadvantage of using relay-based circuitry in manufacturing plants before PLCs was that it was bulky, expensive, and prone to mechanical failure.

Ladder Logic

• Ladder logic was created as the first PLC programming language to simplify programming for electricians and technicians who were familiar with relay-based circuitry.
• Ladder logic is called 'ladder logic' because it resembles a ladder with two vertical rails and a series of horizontal rungs.
• Ladder diagrams are used to program PLCs and describe the logical flow of a program.

Components of Ladder Logic

• The two main components of ladder logic are contacts and coils.
• Contacts are used to examine the status of inputs, and coils are used to control outputs.