Chapter 7, Problem 6RQ

Program Plan Intro

Programmable Logic Controller (PLC):

• PLC is a specialized computer used in industrial segments to control machines and process.
• PLC is program that consists of a set of instructions which resembles the controlling functions needed to perform specific tasks.
• The function of PLC is similar to that of a relay and hence, in an industrial segment a relay is greatly replaced by a suitable PLC.
• When compared to general Personal Computer (PC), a PLC is available in small and tiny sizes.
• The basic architecture of a PLC consists of an input-output interface module and a small Central Processing Unit (CPU) that runs by controlling programming language.

Timer:

• Timer is mainly used to keep an output ON for a specific length of time.
• It provides a preset delay to the control actions.
• In a timer, the output will be energized when the preset value becomes equal to the accumulated value.
• Three different types of timers include Delay-OFF timer, Delay-ON timer and  Delay-ON-Retentive timer.

Explanation of Solution

b.

Resetting the accumulated count to zero:

• The accumulated count of retentive timers can be reset to zero by using a separate reset signal.
• This separate signal is known as Retentive Timer Reset (RES) instruction.
• When RES is true, the accumulated value of the timer is reset to zero...