‘PLC Applications’ is a PLC-based automation project in which students learn step-by-step approaches of implementing an automation system. It involves programming, identifying appropriate I/Os, I/O interfacing & power rating considerations, programme testing and system trouble-shooting. Student will learn the full process of implementing a PLC based project.
Assigned task
For this project, we were tasked with coming up with an improvement to an existing solution to better address the problem.
Issues chosen
Note I will be reusing my presentation slides to aid me in my explanation of my solution
On January 3 2022, Singapore eased covid rules for working in office.
This means more people dining in at hawker centres and food courts. That many people in close proximity increases the risk of spreading COVID.
A way to stem the spread is using ready meal vending machines.
However, ready meal containers are quite hot when coming out of a vending machine.
Give customers an option to add an additional container that insulates the heat. This ready meal will be placed in the container to act as an insulating area. For customers who want to use their own container, they can place their container onto a conveyor belt. This convenor will take the container into the machine and will place the ready meal onto the container.
Proposed solution
Note HMI means Human Machine Interface, which is how a user interacts with a PLC system. For this project the HMI used are a touch screen, a series of push buttons, LED lights, photoelectric sensors and a bi-directional motor.
The HMI that the project was ran on
Conveyor belt system used in project, which was provided by SP
The following slides will provide a step by step guide on how the vending machine works
Root screen
Food selection screen
Container selection screen
Container insertion screen
Summary screen
Preparation screen. TON means ‘On Delay Timer’
Ready screen
Note Unfortunately I did not film a physical demonstration. The footage was filmed using the built-in simulator provided by the PLC software.
PLC program
The following images will illustrate how the PLC programme looks like and its operations.
Used to ‘load’ the vending machine with food and containers
Counts the amount of food and containers left in the machine
Used to undo order and go back one screen
Used to control the summary screen
Used only if user desires to insert own container into machine
Used to signal preparation of food.
Used to send food out of the vending mahcine and to reset all latches, hence allowing a new order to be enterred
