Chapter 2

Micro ProgrammableLogic Controllers

Objectives

• Define a micro PLC.• Explain the advantages of using a micro PLC

in new machine development.• Explain the difference between a micro PLC

and a modular PLC.• Look at an overview of selected

manufacturers’ micro PLCs.

What Is a Micro PLC?

• Typically 32 inputs and outputs or less• Self-contained units• Processor, power supply, and I/O built into

one package

Micro PLC Advantages

• Package size smaller• Lower cost• Less complexity than larger PLCs• Easy installation

Micro PLCs Versus Modular PLCs

• Use when relay replacement and only basic control is desired.

• Micro has smaller footprint.• Micro PLC is less complex than modular.• It is easy to embed micro into machine when

only basic control is needed.• Limited instruction set means easier

programming.

Omron CPM1A Series Micro PLC

• 10, 20, 30, or 40 I/O available• Hand-held programming or SYSMAC

Windows-based software programming• Sinking, sourcing, or relay outputs• Two analog inputs and 1 analog output• Maximum 100 I/O points

CPM1 Ten I/O Micro PLC Features

Image courtesy of Omron Electronics, Inc.

3 MicroLogix 100 Micro Controllers and a Hand-held Programmer

Image courtesy of Allen-Bradley, a Rockwell Automation business

Specifications for Rockwell Automation’s MicroLogix 1500

Image courtesy of Allen-Bradley, a Rockwell Automation business

MicroLogix 1500 Hardware Features

Image courtesy of Allen-Bradley, a Rockwell Automation business

Installing the Processor Unit in the MicroLogix 1500 PLC

Image courtesy of Allen-Bradley, a Rockwell Automation business

Simatic S7-200 Micro PLC

Image courtesy of Siemens Energy & Automation, Inc.