Programmable Controllers And Their Programming

ABSTRACT

Programmable controllers are known as the most widely used electronic devices in the control of production and assembly process in most automated factories due to its simplicity and versatility. A programmable controller is a user-friendly, microprocessor-based, specialized computer carrying out control functions of many types and levels of complexity in industrial applications.
In the coming sections the introduction to company and company profile can be overviewed. This work discusses the overview of programmable controllers and their programming.

ABTRACT

TABLE OF CONTENT

• INTRODUCTION
  • BACKGROUND OF THE STUDY
  • AIM OF THE STUDY
  • SIGNIFICANCE OF THE STUDY
  • ADVANTAGES OF PROGRAMMABLE CONTROLLER
  • DISADVANTAGES OF PROGRAMMABLE CONTROLLER
  • APPLICATIONS OF PROGRAMMABLE CONTROLLERS
  • PROGRAMMABLE CONTROLLER FEATURES
  • PROGRAMMABLE CONTROLLERS BASICS
  • HISTORY BACKGROUND OF PROGRAMMABLE CONTROLLER
  • EARLY METHODS OF PROGRAMMING
  • ARCHITECTURE OF PROGRAMMABLE CONTROLLER
  • PROGRAMMING
  • PROGRAMMING DEVICE
  • LADDER PROGRAMMING

REFERENCES

CHAPTER ONE

1.0                                                        INTRODUCTION

1.1                                           BACKGROUND OF THE STUDY

Programmable Controller is a microprocessor based system that uses programmable memory to store instructions and implement functions such as logic, sequencing, timing, counting and arithmetic in order to control machines and processes (Dunn, 2009).

Programmable controllers can range from small modular devices with tens of inputs and outputs (I/O), in a housing integral with the processor, to large rack-mounted modular devices with thousands of I/O, and which are often networked to other PLC and SCADA systems (Maher, 2019).

They can be designed for many arrangements of digital and analog I/O, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. Programs to control machine operation are typically stored in battery-backed-up or non-volatile memory (Maher, 2019).

Programmable controllers were first developed in the automobile manufacturing industry to provide flexible, rugged and easily programmable controllers to replace hard-wired relay logic systems. Since then, they have been widely adopted as high-reliability automation controllers suitable for harsh environments. This study discusses an overview of the programmable controllers and their programming (Maher, 2019).

1.2                                                     AIM OF THE STUDY

The main aim of this study is to carry out a research on a programmable controller and their programming. The objectives are:

1. To have good knowledge of programmable controllers
2. To study the programming of programmable controllers

1.3                                           SIGNIFICANCE OF THE STUDY

Therefore, the essence of this work is to help the student develop a good general working knowledge of programmable controllers with concentration on relay ladder logic techniques and how the programmable controller is connected to external components in an operating control system.

1.4                       ADVANTAGES OF PROGRAMMABLE CONTROLLER

1. Very fast
2. Easy to change logic i.e. flexibility
3. Reliable due to absence of moving parts
4. Low power consumption
5. Easy maintenance due to modular assembly
6. Facilities in fault finding and diagnostic
7. Capable of handling of very complicated logic operations
8. Good documentation facilities
9. Easy to couple with the process computers
10. Analog signal handling and close loop control programming
11. Counter, timer and comparator can be programmed

1.5                    DISADVANTAGES OF PROGRAMMABLE CONTROLLER

1. There’s too much work required in connecting wires.
   2. There’s difficulty with changes or replacements.
   3. It’s always difficult to find errors; And require skillful work force.
   4. When a problem occurs, hold-up time is indefinite, usually long.

1.6                     APPLICATIONS OF PROGRAMMABLE CONTROLLERS

The batch process in chemical, cement, food and paper industries are sequential in nature, requiring time or event based decisions. Programmable controllers are being used more and more as total solutions to a batch problem in these industries rather than just a tool. In batch process savings are developed principally from reduced cycle time and scheduling. Cycle automation provides rigid control enforcement to eliminate human errors and to minimize manual interventions. Increased efficiency in scheduling is to be expected with maximum utilization of equipment and reduction of fluctuating demands on critical equipment. In large process plants programmable controllers are being increasingly used for automatic start up and shutdown of critical equipments. A PLC ensures that an equipment cannot be started unless all the permissive conditions for safe start have been established. It also monitors the conditions necessary for safe running of the equipment and trip the equipment whenever any abnormality in the system is detected. The programmable controllers can be programmed to function as an energy management system for boiler control for maximum efficiency and safety. In the burner management system it can be used to control the process of purging, pilot light off, flame safety checks, main burner light off and valve switching for changeover of fuels (Byres, 2018)..

1.7                              PROGRAMMABLE CONTROLLER FEATURES

Programmable controllers features can be concluded in the  following:

1. They are rugged, withstand industrial environment, such as heat, humidity, mechanical shocks and vibrations
2. The interfacing for inputs and outputs is inside the controller

• They are easily programmed

1. Programmable controllers are capable of both logic and PID