Programmable Logic Controllers

The book I read to research this post was Programmable Logic Controllers by W Bolton which is a very good book that I bought from a car boot sale. This book was published in 2004 so as a result covers mostly legacy hardware. It is 240 pages so is fairly long. Programmable Logic Controllers are often called PLC’s for short and in the present day it would be CAM or computer aided manufacturing using a language like LISP or Python and maybe something like an Arduino controlling the process. This book uses logic gates with commands like AND, OR and NOT. It would be negative or positive according to conditional inputs. These often have to be programmed in Machine Code using either binary or hexadecimal to represent various commands. Nowadays most kit electronics are going open standard so they can be bought from various manufacturers and you know they will work together. This book does look at components like photo-resisters that are light dependent, reed switches where a magnetic current opens or closes a circuit and also bimetallic switches made with a brass and copper strips joined together so that as they expand unevenly with temperature. The brass expands more than the copper so it bends and touches a contact opening or closing a circuit. These are only a small amount of the components covered. Obviously a lot of the same components are still used for various purposes and this book is of interest in covering this. I bought this book for 50p and would say if you see it for sale somewhere at a low price it may be a worthwhile purchase. I do recommend it.