Project Objective

The objective of this project is to familiarize its participants with steps involved with the design and implementation a PLC system.

Project Description

The purpose of this project is to design and fabricate an interactive carnival style game. The basic layout of the game is made up of six hinged targets, which the contestant can knock down with the three balls supplied to him. The six targets come in sizes of small, medium, and large with values of 30, 20, and 10 points, respectively. When the targets are knocked down the score is totaled on a display. If the total is above 50 points, a light will flash.

Component Listing

Approximately 20’ of 2” by 4” pine

(6)  Limit Switches rated 250 VAC/150VDC
(2)  7 Segment LED displays
(6)  Galvanized Hinges
(1)  DirectLOGIC PLC
    Specs
(1)  DC Light Bulb
(1)  Rest Button

Project Photographes

Scoreboard

Game Unit

Manual

Procedure

Software
Since we decided to have a score limited to 80 points, representing two small targets and one medium target knocked down, we programing the 7 segment display directly from the outputs of the PLC. (i.e. a score of 30 would use a total of five outputs) This design approach is only practical for a limited amount of combinations. The first zero to the left of the decimal point is wired directly to the power supply and is unchanging.

Ladder Logic
 
Inputs/Outputs

Hardware
The fabrication of the base took less than two hours. Mounting of the limit switch proved to be more troublesome than predicted since the positioning of the switches was critical to the hinged targets setting them.  The PLC used for this project had sinking outputs, which created a small problem when we tried to wire the 7-segment LED display. The solution to this problem involved supplying the common grounds for the outputs with the +24VDC supplied by the PLC. After the hardwiring was completed the ladder logic was down loaded into the PLC.