Allen Bradley PLC Programming with RSLogix

Allen Bradley PLCs (Programmable Logic Controllers) are widely used in industrial automation systems. They are powerful devices that can control a wide range of processes and machines. RSLogix is the software used to program these PLCs.

This article will provide an introduction to Allen Bradley PLC programming using RSLogix. We will cover basic concepts and demonstrate how to create a simple program.

What is a PLC?

A PLC is a computer that is specifically designed for industrial control applications. It has the following key features:

• Robust and reliable: PLCs are built to withstand harsh industrial environments.
• Programmable: They can be programmed to perform a wide range of tasks.
• Input/Output (I/O) capabilities: PLCs have inputs that receive signals from sensors and outputs that control actuators.
• Real-time operation: PLCs can process data and respond to changes in real-time.

What is RSLogix?

RSLogix is a software package from Rockwell Automation that is used to program Allen Bradley PLCs. It provides a graphical user interface (GUI) that makes it easy to create and edit PLC programs.

Basic Concepts of PLC Programming

PLC programming involves creating a program that tells the PLC what to do. The program is written in a ladder logic language, which is similar to electrical circuit diagrams.

Here are some basic concepts of PLC programming:

• Inputs: Inputs are signals that are received from sensors. They can be digital (on/off) or analog (a continuous range of values).
• Outputs: Outputs are signals that are sent to actuators. They can also be digital or analog.
• Logic gates: Logic gates are used to perform logical operations on input signals. Common logic gates include AND, OR, NOT, and XOR.
• Timers and counters: Timers and counters are used to measure time intervals and count events.
• Program organization: PLC programs are typically organized into routines and tasks.

Creating a Simple PLC Program

Let's create a simple program that controls a motor based on the state of a switch.

Step 1: Define Inputs and Outputs

We need to define the inputs and outputs that our program will use. In this example, we will use a digital input for the switch and a digital output for the motor.

Step 2: Create the Ladder Logic Program

The following ladder logic program will turn the motor on when the switch is closed and turn it off when the switch is open:

|---[Switch]---|---[Motor]---|

This program consists of a single rung. The left side of the rung represents the input (switch) and the right side represents the output (motor). When the switch is closed, the rung is energized, and the motor is turned on. When the switch is open, the rung is de-energized, and the motor is turned off.

Step 3: Test and Debug the Program

Once the program is created, it should be tested and debugged to ensure that it works correctly. This can be done using a simulator or by running the program on the actual PLC.

Conclusion

This article has provided a basic introduction to Allen Bradley PLC programming using RSLogix. We covered basic concepts such as inputs, outputs, logic gates, timers, and counters. We also demonstrated how to create a simple PLC program.

PLC programming is a powerful tool that can be used to control a wide range of industrial processes. With the help of RSLogix, it is relatively easy to create and edit PLC programs. By understanding the basic concepts and following the steps outlined in this article, you can start programming your own Allen Bradley PLCs.