PLC02: Traffic Lights
A Programmable Logic Controller, or PLC, can be used to control
any process that requires automation, such as processes found in
a chemical plant, automated machinery, or laboratory equipment.
When used in such a process, the PLC is programmed to perform a
set of logical steps in a specific order to complete the desired
task. These steps are programmed into the PLC using a ladder
logic program, which consists of a specific set of instructions
which will be used to define the process and control the machine.
This PLC experiment allows traffic light control of crossroads using a timed sequence. The control program can be developed to cope with interrupts from pedestrian crossing requests or off-peak vehicle detector inputs.