Programmable Logic Controller (PLC) Lab

The PLC lab contains multiple workstations equipped with computers, PLC units and other interfacing devices to train students how to program and upload ladder logic code. Students program ladder logic code using the RSLogix software, which provides a graphical interface representing conditional computer programming functions such as if/else statements. The lab is based primarily on the Allen Bradley family of Programmable Logic Controllers, which are widely used in factories and other settings.

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Lab Objective

The primary objective of the PLC lab is to familiarize students with how signals from input devices (i.e. switches, sensors, etc.) can interface with PLC units in order to invoke certain actions (i.e. start/stop an electric motor, turn on a light, etc.). A PLC functions similar to your computer. A computer processes input (i.e. keyboard entries, sounds from microphones, etc.) and invokes a certain output (i.e. showing the letter you typed on the screen, sending a request through the internet, etc.). Similarly, a PLC unit processes input and invokes output, but the inputs to a PLC unit are usually devices such as sensors, buttons, switches, etc. The outputs are usually signaling to start/stop motors, turn on/off lights, sound a horn, etc.

One example of where PLCs are used is in traffic lights. The inputs for traffic lights are induction loops that are installed into the streets themselves. When your car goes over the loop, it changes the inductance of the loop, which can be detected by a sensor and signaled to the PLC unit. The PLC unit can then react to that signal by processing it based on a specific ladder logic program that it is running. For example, the ladder logic can be programmed to set a timer to change all the other lights to red and then change the light for the lane your car is in to green. Other examples include controlling conveyor belts and other devices prevalent in manufacturing plants and other industrial settings.

PLCs are commonly used to control traffic lights

Project Examples

Students complete multiple ladder logic based projects in the plc lab. Each project gets progressively more difficult as additional input and output states are added to the project deliverables.
Projects typically include, but are not limited to, the following:

Industrial Door

In this project, which is used to introduce students to basic concepts of ladder logic, students use the LogixPro simulator to create an industrial door that opens and closes based on various sensor inputs. This type of door is commonly used in warehouses and is big enough to allow a large vehicle (the size of a bus) entry.

Silo Simulator

Students build an Automatic Drum Filling system in this simulator. Each drum will contain the exact same amount of fluid and the output rate can be changed by the user. It should be able to be stopped and re-started at any time, and run on a conveyor. The Silo Simulator resembles what students would use in manufacturing and works much like an assembly line.

Batch Mixing

The batch mixing simulator familiarizes students with the mixing processes by teaching them how to use sensors in large tanks to monitor changes in concentration of different materials.

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