PLC Programming for Industrial Automation Textbook

DRAFT
PLC Programming for
Industrial Automation
Kevin Collins
Formatted & updated by
Scott Willis
December 2014
(Note: This is not a completed document)

Contents
Introduction................................................................................. 1
1. PLC Basics................................................................................... 1
1.1 Function of a PLC........................................................... 2
1.2 Inputs and Outputs......................................................... 2
1.3 PLC Architecture and Wiring Diagrams...................... 4
1.4 Network Protocols........................................................... 5
Questions.......................................................................... 5
2. Ladder Programming.................................................................. 8
2.1 Conditional Logic............................................................. 8
2.2 Ladder Diagrams............................................................. 9
2.3 Normally closed contacts................................................10
2.4 Outputs and latches.........................................................11
2.5 Internal relays..................................................................15
2.6 Timers...............................................................................15
2.7 The Pulse Generator........................................................19
2.8 Counters............................................................................21
Questions and exercises....................................................24
3. Sequential Programming..............................................................29
3.1 Introduction.......................................................................29
3.2 A Simple Automation Sequence.......................................29

3.3 Evolution of the Sequential Function Chart....................32
3.4 Programming using the Sequential Function Chart.......33
3.5 Entering the SFC program into the PLC.........................35
3.6 Modifying an SFC Program...............................................43
3.7 Use of Timers and Counters in SFC Programming.........44
Questions and Exercises......................................................51
4. Selective Branching..........................................................................60
4.1 Introduction..........................................................................60
Questions and Exercises.......................................................79
5. Parallel Branching.............................................................................89
5.1 Introduction............................................................................89
5.2 Parallel Branching and the SF chart....................................89
Appendix A: Using the TriLogi software........................................A1