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Nowadays control is very essential part of every sector. Most of industries depends on control. In this session have to make projects such as Automated Selection machine which is a similar industrial process control application.
Aim and Objectives :
The report was produced in accordance to the project of Automated Selection Machine. The objectives of the project were given below.
Design Ladder Logic and Sequential Function Chart on a PLC
Draw a list of required input and output switches and sensors
Design automated selection machine on E1071 Human Machine Interface.
After that test Ladder Logic and Sequential Function Chart for the automated selection machine with HMI and PLC in real time.
Name of Projects :
Project 1: A Fire alarm which is place in outside and switches are in five rooms when fire occurred fire sensor will be working so outside will be alarmed. If we switch off any switch alarm will be stopped.
Project 2: A machine such as conveyor carries two different types of products here use red and green balls. That is essential to pass both balls to two separate channels and to be packaged separately.
Computer (PC) connected with network :
For making project computer is essential as PLC, HMI all are operated with by computer. All data are download by help of computer. Even now a days control system can not imagine without a computer
Programmable Logic Controller (PLC) :
Programmable logic controller (PLC) is a device that was sequential relay circuits for machine control. The PLC works by looking at its inputs and depending upon their state, turning on/off its outputs. The user enters a program, usually via software)is a digital computer used for automation industrial processes. For this project we use Mitsubishi PLC. PLC is designed for multiple inputs and output, extended temperature ranges impact. PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time. PLCs contain input and output devices compatible with industrial pilot devices and controls and the design problem centres on expressing the desired sequence of operations in ladder logic and sequential function chart.. PLCs are "real world" applications.
Human Machine Interference (HMI) :
Human machine interfaces (HMI) are operator interface terminals which in order to control devices. Human machine interfaces include knobs, indicators, levers, and controls. It provides programmable function keys or a full key pad. Devices that include a processor or interface to personal computers (PCs) are also available. Selecting human machine interfaces include devices supported and devices controlled. operating temperature, operating vibration and shock ratings other factors.
Software- GX IEC developer :
GX IEC Developer is more powerful programming and documentation package. It supports your entire PLC implementation from the initial project planning operation. Top-down architecture, structured programming, comprehensive printed documentation and support for user-defined help for your function blocks
Software- E Designer :
The E Designer programming software it very easy to create and edit projects for HMI. The software's utility provides a complete graphical overview of the project.Â The package comes complete with a library of ready to use factory floor symbols. This is unicode support and dual driver support
Some manuals :
Only manual can give a basic and root idea as well as operation of any Product. In this project, uses manual for Mitsubishi Programmable logic controller (PLC) for build ladder logic and Sequential Function Chart. Also use the manual of E Designer for develop the overview.
Method and Implementation :
Programmable Logic Controller (PLC) is connected with Human Machine Interference (HMI). By using GX IEC developer design ladder logic and Sequential Function Chart. Ladder logic is a method of drawing electrical logic schematics. Ladder logic has contacts that "make" or "break" "circuits" to control. Ladder logic depends on some symbol of switches such as
--[ ]-- Means open switch it has value '0' ( Input)
--[ / ]- Means close switch 'it has value '1' ( Output)
-( )-- It shows the output
[ ] ( )
The symbols used in Ladder Logic consists of a power rail to the left, a second power rail to the right, and individual circuits that connect the left power rail to the right. The logic of each circuit is solved from left to right. .
The picture above has a single circuit.
If Input1 is ON (or true) - power (logic) completes the circuit from the left rail to the right rail - and Output1 turns ON (or true).
If Output1 is OFF (or false) - then the circuit is not completed and logic does not flow to the right - and Output 1 is OFF. Â
There are many logic symbols available in Ladder Logic - including Timers, Counters. Counters are very essential in ladder logic programming. Counters are used to index, increment or decrement values. Timers gives the precision in time. Timer on delay starts timing when instruction is true. Timers are used to track time when instruction are on or off. This design depend on logic gate.
Now PLCs have many types of special blocks. They include timers, arithmetic operators , counter and comparisons. PLC works by continually scanning a program. PLC scan cycle as consisting of 3 important steps. There are typically more than 3 but here focus on the important parts. Typically the others are checking the system and updating the current internal counter and timer values.
A PLC scan
Figure : 3 important steps.
Next step is develop the project by E Designer. E Designer programming software used to create and edit projects for the control units E Designer provides images for specific components which is suitable for process control applications. For example it provides various type of switches, indicators, diagram. clock etc. Check the project in Human Machine Interference (HMI).
After that make the Sequential Function Charts (SFC) of projects Sequential Function Charts (SFC) is a graphical technique for writing control programs. Steps in an SFC diagram can be active or inactive. Actions are only executed for active steps
Start block is at top of the program defines the beginning. Initial block is the next block after start block. This is the programmable controller starts function chart execution and returns to this step from the end of the program unless directed otherwise by the program logic. This block is identified by a double-sided box. Step block is the function chart's basic unit and contains ladder logic for each independent stage of the process. It is identified by a single-sided box.
For project1, design the ladder logic with help of GX IEC developer. Design five switches and one output. This design based on logic OR gate. The ladder logic of project 1 given below
Figure : Ladder Logic for Project 1
Then download the project and design in Human Machine Interference (HMI). Project on HMI shown below.
Figure : Project1 on HMI Screen
After that draw the Sequential Function Chart for Project 1 by using GX IEC Developer. When fire occurred switch on any of tem then it alarmed or lighted ,If turn off any switch then alarm will be off.
For Project 2, Draw the ladder logic. Here use timer and this project is based on AND gate ,OR gate. Ladder logic of project 2 given below.
Figure : Ladder logic for Project 2
When switch X0 then Y0 on means light on means motor is running. If X2 on then Y1 will be turned on this is for Green ball. If X3 turn on then Y2 will be highlighted means Red ball selected.
Draw the overview in Human Machine Interference (HMI) and sequential function chart. Project on Human Machine Interference (HMI) shown below. After 2.5 Second sensors will be working then ball will be separately highlighted.
Figure : Project 2 in Human Machine Interference (HMI)
Evaluation of results/Outcome :
In Project 1 designed on based of OR gate. When fire alarming if turn of any switch then alarm will be off. This Here use five switches and one timer and time duration is 10 seconds. If see fire alarm any switch then alarm will be working after 10 second. In view it is working. This is very simple and less expensive fire alarm. In Project 2 is made by 3 Timer. At first when turn on motor switch then motor is running balls come towards sensor. When Green sensor working then Green Balls go through the conveyor and fall in box. In other hand when Red sensor worked then Red ball fall in the box. This machine can be used for different products to separate.
In both projects are made in simple way which is easy to operate and less expensive. There are some limitations has been faced to make that projects. Fire Sensor is not added in this fire alarm.
The report shows most of the aim and objective of projects were successfully met. Design ladder logic for the machine. Download project in PLC. Design the machine in Human Machine Interference (HMI). Projects are working properly. Make the project in given time.