Than its hard-wired components, made these changes easier for the technician and also more cost efficient for the industry. The ability to modify controls within the “ladder logic” of a machine’s “controller”, rather Programmable Logic Controllers or “PLC’s” were developed during the 1960’s to meet the ever-changing needs of the automobile industry, where products changed yearly and made frequent modifications to wiring and relay-based control As old machines were replaced with newer PLC controlled equipment, machineĭowntime became less frequent and we discovered that troubleshooting a fault or problem could be much easier to During the early 80’s the company I worked for began integrating PLC’s – “programmable logic controllers” into existing equipment and a new world of possibilities for machineĪnd process control opened up. This made the basic control of equipment very difficult to alter or modify. In addition to this, the “logic” of the machine was basically “hard-wired” – control relay to control relay, by what seemed like miles of wire. It was not uncommon to see electrical schematics on large 3’x 6’ sheets which often made troubleshooting a daunting task. During that period, this world was pretty much dominated by large grids of electro-mechanical relays and timers that were used to provide the control “logic” these machines required to perform their task. In the mid 70’s I began my journey into the world of troubleshooting machine technology and automation.
For these reasons, it is important to develop a solid knowledge of the whole concept of PLC programming instructions, what they do, how they work, and how to build a program from these instructions that will accomplish a desired result.
There are many different controllers on the market, each with their own unique application and development software, different communication software and protocols, and nuances in their program instructions sets. While the use of PLC’s in automation and control is widespread, it is not necessarily always easy or straightforward to program and troubleshoot equipment.
The use of PLC’s and Process Automation Controllers is widespread throughout industry, and the need for technicians who are skilled in these areas, together with electrical and electronics troubleshooting skills, I believe has never been greater than it is today. The goal is to gain proficiency and build confidence in your programming abilities. “Table of Contents”, the whole focus of this book is to take you in a step-by-step journey through “basic” PLC As you can tell by simply reading over the The best way to gain proficiency in any difficult subject is to develop a solid understanding of the “basics”, which thenīecome a foundation for necessary skills and abilities in any field of endeavor. Programming PLC’s, then I believe this book will greatly benefit you! Preface: Goals & Focus! If you need to gain familiarity and confidence with PLC programming, but have never had the benefit of formal training in
(OTL – Latch), (OTU – Unlatch), (OSR - One-Shot-Rising), (TON - On-Delay Timer), (TOF - Off-Delay Timer) Example Program! Memory Usage – “Good” Programming Practices! Chapter 6: Program Documentation Address Symbols & Descriptions! Rung Comments Program Verification Concluding Comments!
Anderson Copyright 2015 Gary D AndersonĬontents Preface: Goals & Focus! Chapter 1: Introduction to Programmable Logic Controllers Sensors, Actuators & Objectives PLC Architectures & Systems CPU – Central Processing Unit Power Supply Programming Interface Communication – Drivers & Interface Cable Chart PLC Inputs & Outputs Chapter 2: Input & Output Modules Termination, Threshold Detection, Optical Isolation, Translation & Indication Input Module Function Output Module Function Wiring Power & Field Devices Sinking & Sourcing Modules Master Control Diagram Digital Input Module, Digital Output Module Chapter 3: Addressing, Memory, and Scan Routine Configuring a PLC Project Addressing Module-Location Dependent addressing General Syntax Chart Addressing the B3, N7 and F8 Data Files Addressing Timers and Counters User-Defined Addressing Scan Routine Chapter 4: Basic Instruction Types Question Asking InstructionsĪction Instructions Register type instructions Example of “XIC”, “XIO” and “OTE” functions Chapter 5: Logical Operations & Arrangement of Instructions: AND, OR, NAND, NOR, XOR Additional types of “Action-Performing” Instructions. PLC Programming using RSLogix 500 Basic Concepts of Ladder Logic Programming! Book 1 By Gary D.