3442 Industrial Instruments 2 Chapter 8 Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 Princess Sumaya Univ. Electronic Engineering Dept. 3442 Industrial Instruments 2 Chapter 8 Discrete-State Process Control Dr. Bassam Kahhaleh Dr. Bassam Kahhaleh

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Definitions The discrete state of the process at any moment is the set of all input and output values. An event in the system is defined by a particular state of the system, i.e. particular values of inputs and outputs. A discrete-state process control is a particular sequence of events through which the process accomplishes some objective

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Example Frost-free refrigerator/freezer Discrete-state I/P Door open/closed Cooler temp. high/low Freezer temp. high/low Power switch on/off Frost detector on/off Frost eliminator timer out/not out

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Example Frost-free refrigerator/freezer Discrete-state O/P Light on/off Compressor on/off Timer on/off Heater on/off Baffle open/closed

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Discrete-State Variables Continuous Control

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Discrete-State Variables Continuous Control Discrete Control

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Discrete-State Variables Continuous Control Discrete Control Composite Discrete/Continuous Control

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Process Specifications Process Objectives Process Hardware Input Devices Limit Switches Comparators Push Buttons Output Devices Lights Motors Solenoids

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Event Sequence Description Narrative Statements Flowcharts Binary-State 00 01 1X X / 0 1 / 1 0 / 0 X / 1

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Event Sequence Description Flowchart Example

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Event Sequence Description Flowchart Example

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Event Sequence Description Binary-State Example Fill the tank to level A from valve A. Fill the tank to level B from valve B. Start the timer, heat, and stir for 5 minutes. Open output valve C until the empty switch engages.

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Event Sequence Description Binary-State Example I/P Variables LA LB LE TU O/P Variables VA VB VC TM S H

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Event Sequence Description Binary-State Example State: LA LB LE TU VA VB VC TM S H

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Relay Controllers & Ladder Diagrams Control Relays (Relay Sequencer)

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Relay Controllers & Ladder Diagrams Ladder Diagram

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Relay Controllers & Ladder Diagrams Ladder Diagram Example

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Relay Controllers & Ladder Diagrams Ladder Diagram Example

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Relay Controllers & Ladder Diagrams Ladder Diagram Example

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Relay Controllers & Ladder Diagrams Ladder Diagram Example

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Relay Controllers & Ladder Diagrams Ladder Diagram Example When the START button is pushed, the platform is driven to the down position. When the STOP button is pushed, the platform is halted at whatever position it occupies at that time. When the UP button is pushed, the platform, if it is not in downward motion, is driven to the up position. When the DOWN button is pushed, the platform, if it is not in upward motion, is driven to the down position.

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Relay Controllers & Ladder Diagrams Ladder Diagram Example Start Stop

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Relay Controllers & Ladder Diagrams Ladder Diagram Example START STOP Power

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Relay Controllers & Ladder Diagrams Ladder Diagram Example START ↓ Motor STOP Power

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Relay Controllers & Ladder Diagrams Ladder Diagram Example START ↓ Motor UP ↑ Motor STOP Power Down

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Relay Controllers & Ladder Diagrams Ladder Diagram Example CR CR

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Hardwired Programming Relay Sequencers Programmable Logic Controllers (PLCs) Processor Input Modules Output Modules

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Programmable Logic Controllers (PLCs) Input Module

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Programmable Logic Controllers (PLCs) Output Module

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Programmable Logic Controllers (PLCs) Logic Programming Using a NC switch to turn off a light with relay logic and with PLC programming: The button turns the light OFF. With relay logic the button turns the light ON. With a PLC program the button turns the light ON

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control Programmable Logic Controllers (PLCs) Logic Programming NO switches are considered INACTIVE when they are read as open circuit, and ACTIVE when they are read as closed circuit. In the ladder diagram, 01 must be ACTIVE while 03 must be INACTIVE to turn 08 ON.

8: Discrete-State Process Control Princess Sumaya University 3442 - Industrial Instruments 2 8: Discrete-State Process Control End of Chapter 8