An Introduction to PLC programming
A PLC or Programmable Logic Controller is an electronic or computer device used for industrial control systems. PLCs run a program that manages inputs and logically turns outputs on/off to obtain the desired control. This article will cover the general structure of a PLC program. PLC programming An instruction or job order is formed by two main parts: operation and function. The function is the complement of the operation and is divided into symbol and parameter. The operation determines the CPU’s job or the kind of instruction that it must execute, and the function determines the address. The address, in turn, indicates where the CPU should execute the instruction of elements such as counters, timers, I/O, and internal marks. Basic examples of instructions are: LD: (4C) Loads the line LDN: (42) Negation of the operation LD AND: (41) AND logic ANDN: (44) Negation of the operation AND OR: (4F) OR logic To write a program, other kinds of instructions called service instructions are...