Laboratory 3 : Traffic Light Control Using a PLC and Automation Studio
Purpose: The purpose of
this laboratory exercise is to develop a control system for a traffic light using Automation Studio. The
system will be developed using the Allen-Bradley PLC
module. The traffic light system is used to control an
intersection with no signalling of turns. Timers are used to control the traffic light in one (north/south direction).
Timers are essential to assure safe
maneuvering through the intersection. The last activated signal (light) will
remain in control until a time allows the traffic light to chang. Note: A previously created HMI
system will be
provided. Your task is to only create the PLC program
and link the appropriate tags. A service disconnect switch should
be added to allow for maintenance. Once the service
disconnect has been activated to the ON position, the traffic light
should run in automatic mode. A counter will be used to
monitor the traffic flow in the north/south bound lanes. Finally, a
simulation will be run to verify the
successful operation of the system.
Outcomes: After completing this laboratory exercise students should be able to demonstrate the following abilities and skills:
1. Demonstrate basic knowledge and application of
selected modules within the Automation Studio software suite;
2. Demonstrate skills in the use of
Automation Studio to create a PLC control
program, and link to a HMI panel;
3. Demonstrate knowledge of timers required for on-delay control within a PLC;
4. Demonstrate knowledge of counters required for tracking cycles within a PLC;
5. Demonstrate successful completion of the
laboratory exercise through a verified system simulation;
6. Demonstrate an understanding of the conveyor
control system and control through a written laboratory report.
Deliverables: The following deliverables are required for this laboratory exercise:
1. Traffic light system with components clearly labeled;
2. PLC program with all inputs, outputs and functions
clearly identified;
3. Internal connections of a timer and counter within the PLC program;
4. Wiring diagram showing connections of inputs, outputs,
and power source to the PLC output interface module;
5. HMI panel diagram clearly labeled;
6. Table of all tags used for the laboratory;
7. A formal written report including the following
sections:
I. Abstract (10 points)
II. Problem Statement (5 points)
III. Required System Operation (10 points)
IV. System Diagram (10 points)
V. Procedures (10 points)
VI. Results: (25 points)
A. Sequence Control Chart (5)
B. Symbols Table (5)
C. Tags Table (5)
C. Diagrams (Pneumatic circuit, PLC program, wiring
diagram, HMI panel layout) (10)
VII. System Analysis and Summary (30 points)
A. Detailed explanation of system configuration and operation;
(10)
B. Network by Network explanation of PLC program control; (15)
C. Recommendations (5)
VIII. References
System Overview: The system operation is controlled by an HMI operator interface (provided). Once Automation Studio is placed in the
simulation mode and the operator activates the service disconnect
switch to the on position, a traffic light system is used
to control an intersection (with no signalling of turns). Timers will
be needed to
assure safe
maneuvering through the intersection.
The last activated state will remain in control until a timer controls
flow from the
opposing direction. Note: A previously
created HMI system will be provided. Your task is
to only create the PLC program
and link the appropriate tags. A
service disconnect switch shoul be added to allow for
maintenance. Once the service
disconnect has been activated to
the ON position, the traffic light should run in automatic
mode. Counters are used to
monitor the traffic flow in both the
north/south bound lanes.
Diagram of Completed System:
An illustration of the system
showing the HMI traffic system is shown
below.
Procedures
A. 1. Create a list on required inputs and outputs for the PLC
program. Develop a pencil and paper sketch of the PLC program and
identify the basic
components
required. Develop a symbol table with cross referencing.
2. Develop a control sequence
chart showing the logical constraints. The purpose of the chart
is to provide a guide for writing the logical
programming steps. The sequence control chart could be compared
to a flow chart usage for computer programming.
3. Develop a pencil and paper
sketch of the PLC program and identify the basic components required.
B. Load the system HMI as as shown above in Automation
Studio. Follow the procedures as outlined in class lecture by
completing the following steps:
1. Using the AB-PLC
module, create the control circuit including a appropriate inputs, outputs, timers, and counters.
2. Open the Variable Manager and create the appropriate TAGS:
3. Note: Internal tags
will be created automatically when components are created in Automation
Studio. A table of existing tags can be viewed within the
Variable Manager for this project is . You may elect to add additional
tags as needed.
4. Link the tags to the appropriate component as demonstrated in class.
C. Run a simulation of the project to test for
functionality. Verify that all active components are simulated
and working properly.
Run the simulation in slow motion or
"step-by-step" and observe the logical operation. Study the
system's operation until you have
a thorough understanding of how the system operates and how control is executed.
D. Using the format specified, complete a written laboratory report and submit by next class period.
