figure 8.1 process and controller. curtis johnson process control instrumentation technology, 8e]...

FIGURE 8.1 Process and controller.

Curtis JohnsonProcess Control Instrumentation Technology, 8e]

Copyright ©2006 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458

All rights reserved.

FIGURE 8.2 Refrigerator/freezer system inputs and outputs.




FIGURE 8.3 Continuous control of level.




FIGURE 8.4 Discrete control of level.




FIGURE 8.5 Composite continuous and discrete control.




FIGURE 8.6 Objectives and subobjectives of a process.




FIGURE 8.7 A discrete-control process.




FIGURE 8.8 Completion of the initialization phase of the process shown in FIGURE 8.7.




FIGURE 8.9 Basic flowchart symbols.




FIGURE 8.10 Part of the initialization flowchart for FIGURE 8.7.




FIGURE 8.11 Tank process for Example 8.4.




FIGURE 8.12 Oven system for discrete control.




FIGURE 8.13 Use of a relay and switch to start a motor.




FIGURE 8.14 Use of momentary push-button switches and a relay to implement a latch.




FIGURE 8.15 Symbols of input devices used in ladder diagrams.




FIGURE 8.16 Symbols of output devices used in ladder diagrams.




FIGURE 8.17 Symbols for switches used in ladder diagrams.




FIGURE 8.18 Ladder diagram to control two lights.




FIGURE 8.19 Elevator system for Example 8.6.




FIGURE 8.20 Initialization to move platform down when the START button is pushed for Example 8.6.




FIGURE 8.21 Ladder diagram for the STOP sequence of Example 8.6.




FIGURE 8.22 The complete ladder diagram for Example 8.6.




FIGURE 8.23 A simplified ladder diagram for Example 8.6.




FIGURE 8.24 Solution for Example 8.7.




FIGURE 8.25 Basic structure of the programmable logic controller (PLC).




FIGURE 8.26 Typical wiring to a PLC input module.




FIGURE 8.27 Typical wiring to a PLC output module.




FIGURE 8.28 PLC scan time puts restrictions on the speed of events.




FIGURE 8.28 (continued) PLC scan time puts restrictions on the speed of events.




FIGURE 8.29 Hand-held PLC programming unit.




FIGURE 8.30 Desktop terminal PLC programming unit.




FIGURE 8.31 Using an NC switch to turn on a light with relay logic and with PLC programming: (a) Wrong, the button turns the light OFF; (b) with relay logic, the button turns the light ON; and (c) with a PLC program, the button turns the light ON.




FIGURE 8.32 Physical connections to the PLC (a) and the programmed ladder diagram (b) for a motor start/stop system.




FIGURE 8.32 (continued) Physical connections to the PLC (a) and the programmed ladder diagram (b) for a motor start/stop system.




FIGURE 8.33 Physical elements for Example 8.9.




FIGURE 8.34 Wiring and program solution for Example 8.9.




FIGURE 8.35 The basic PLC counter.




FIGURE 8.36 Program and timing solution to Example 8.10.




FIGURE 8.37 PLC timer functions: (a) simple timer, (b) accumulating timer.




FIGURE 8.38 Solution to Example 8.11.




FIGURE 8.39 Chemical system for Example 8.12.




FIGURE 8.40 PLC program solution for Example 8.12.




FIGURE 8.41 Tank system for Example 8.13.




FIGURE 8.42 Physical ladder diagram for Example 8.13.




FIGURE 8.43 Programmed ladder diagram for Example 8.13.




FIGURE 8.44 System for use in Problems 8.8 and 8.14.




FIGURE 8.45 Process for Problems 8.11 and 8.16.




FIGURE 8.46 Motor and switches for Problem 8.15.




FIGURE 8.47 System for Problems S8.1, S8.2, and S8.3.




FIGURE 8.48 Hydroponic system for Problem S8.4.




figure 8.1 process and controller. curtis johnson process control instrumentation technology, 8e]...

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upper saddle river

pearson education

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discretecontrol process

tank process

discrete control of

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