This project aims to automate a car parking barrier system using a PLC microcontroller. A car parking barrier controls entry using barrier arms. The automated system will allow or disallow entry based on verification by coin counter or barcode reader. A PLC uses ladder logic programming to control the inputs of entry/exit sensors and outputs of entry/exit barriers and indicator lights. When the entry sensor is activated, the barrier opens for 2 seconds to allow entry and then closes. The number of parked cars is counted and the full light illuminates when maximum capacity is reached. This automated PLC-controlled system provides an organized means of parking cars.

2. Purpose of Project
The purpose of this project is to make an automated car
parking barrier system. In car parking lots
and parking garages, entry is controlled
using barrier systems. Now there must a coin counters or
bar code reader which allows the passenger to show its
verification for the entry in parking lot. So we have make
automated system of this barrier to allow or dis allow a car
entry in parking lot using PLC microcontroller in in this
parking barrier.

3. Car Parking Barrier
Car parking barrier also known as a boom gate. It is a bar, or pole
pivoted to allow the boom to block vehicular access through a controlled
point. Typically the tip of a boom gate rises in a vertical arc to a near
vertical position. Boom gates are often counter-weighted, so the pole is
easily tipped. Boom gates are often paired either end to end, or offset
appropriately to block traffic in both directions.
Boom gates are typically found at Level Crossings, drawbridges, parking
facilities, checkpoints and entrances to restricted areas. They are also
the usual method for controlling passage through toll booths

4. Automated Car Parking System
There are various technologies for an automatic car
parking barrier. One of them is electro-mechanical, which
is widely used due to its reliability.
An automatic car parking barrier can be operated through:
a) Push Button
b) Remote Control
c) Tags / Card Reader
d) Loop Detectors

5. PLC Program
PLC stands for Programmable Logic Controllers. They are
basically used to control automated systems in industries. They
are one of the most advanced and simplest forms of control
systems which are now replacing hard-wired logic relays at a
large scale.
A basic PLC system consists of the following sections:
i. Input/ Output Section
ii. CPU or Central Processing Unit
iii. Programming Device
iv. Memory
v. Power Supply

6. Working of a PLC

7. Programming in PLC
A program loaded into PLC systems in machine code, a
sequence of binary code numbers to represent the
program instructions.
Assembly language based on the use of mnemonics can
be used, and a computer program called an assembler is
used to translate the mnemonics into machine code.
High level Languages (C, BASIC, etc.) can be used.

8. Ladder Logic PLC Programming
Ladder logic diagram is the most basic and simplest form of
programming the PLC. The below figure shows the hardwired-
ladder diagram wherein the same lamp load is controlled by two
push button switches, In case if any one of the switches gets
closed, the lamp glows. Here two horizontal lines are called
rungs which are connected between two vertical lines called
rails. Each rung establishes the electrical continuity between
positive (L) and negative rails (N) so that the current flows from
the input to output devices.

9. Steps of programming PLC using Ladder
Logic
1. Analyze and Get the Idea of Control
Application.
2. List All the Conditions and Get the Design
using Flowchart.
3. Open and Configure the PLC Programming
Software.
4. Add the Required Rungs and Address Them.
5. Check the Errors and Simulate It.
6. Download the Program to PLC CPU Memory.

10. PLC in automated car parking barrier system
A ladder logic PLC program is used for this system. There are
two inputs (Sensors) which are Entry sensor and Exit sensor.
Also four outputs those are Entry barrier, Exit barrier and two
indicating lights. One light indicates available space and other
light indicates about unavailable space.

11. Opening of Barrier for the Cars
When switch ON, system will start. Already SPACE light will
glow. If Entry sensor active, entry barrier motor will rotate
clockwise direction two seconds. It is mentioned in blue color
indicator (Barrier is opening for a car). Eight timers are used for
each functions. Gate is opened for few seconds. It is indicating
with pink color (Barrier is opened).

12. Barrier closing after cars passed
After five second entry barrier motor will rotate
anticlockwise two seconds to close the barrier.

13. Cars parked in its parking location
Counting the number of cars. When reached maximum
number, SPACE indicator light will get off and FULL light
will get indicate.

14. Conclusion
Now this project we showed a PLC program that can
be used to park the cars in the parking lot with
systematic automated barrier. Barriers opens when
the system allows the cars to pass through it and
closes when a car or a required amount of cars are
passed by the barrier. This system can be used in
shopping malls parking lots, office parking lot and for
any other organizations parking system.