Programming Allen Bradley PLCs: A Beginner’s Guide

Allen-Bradley PLCs are some of the most widely used automation controllers in industrial environments. Whether you're stepping into the world of industrial automation or upskilling as a technician or engineer, learning how to program Allen-Bradley PLCs is a powerful career move.

This beginner-friendly guide walks you through the essentials of programming Allen-Bradley PLCs using RSLogix 500 and Studio 5000 the two most common Rockwell Automation platforms.

 Step 1: Understand What a PLC Is

A Programmable Logic Controller (PLC) is an industrial computer used to automate machinery and processes in manufacturing, packaging, material handling, and more. It reads input signals (like switches or sensors), executes a programmed logic sequence, and then controls outputs (such as motors or valves) in real time.

Allen-Bradley PLCs, built by Rockwell Automation, are known for:

• Rock-solid reliability

• Easy-to-use programming environments

• Scalable architecture (from MicroLogix to ControlLogix)

 Step 2: Set Up Your Software

You’ll need the right Rockwell software based on the PLC model you're working with:

To get started:

• Visit Rockwell Automation's website to download software.

• Install RSLinx Classic (for communications).

• Activate your license using FactoryTalk Activation Manager.

Example: Use Studio 5000 to program a 1769-L24ER CompactLogix 5370 controller for a smart assembly line.

 Step 3: Connect to Your PLC

Connecting your PC to the PLC is essential before you can begin programming.

Steps:

1. Use an Ethernet, USB, or serial cable depending on your PLC model.

2. Open RSLinx and verify communication via the RSWho utility.

3. Set your PC’s IP address to match the PLC’s subnet.

Pro Tip: For CompactLogix or ControlLogix over Ethernet, use BOOTP/DHCP utility if the IP address needs configuration.

 Step 4: Create a New Project

Now that you're connected, it's time to create your project.

1. Launch Studio 5000 or RSLogix 500.

2. Choose New Project.

3. Select the exact PLC model and firmware version.

4. Name your project and define hardware modules (I/O cards, power supply, etc.).

Example: In Studio 5000, select ControlLogix 1756-L83E, and configure I/O modules like 1756-IB16 (digital input) and 1756-OB32 (digital output).

 Step 5: Write Your First Ladder Logic Program

Allen-Bradley PLCs primarily use ladder logic, a visual programming language that resembles electrical relay schematics.

To create a basic motor control program:

1. Open the Main Routine in the ladder editor.

2. Add a rung using an XIC (Examine If Closed) instruction for a Start Button.

3. Add an OTE (Output Energize) for the Motor Output.

4. Include a Seal-In (latching) contact for holding the motor ON.

Simple Motor Start/Stop Logic:

 Step 6: Download and Test Your Program

Now it’s time to bring your program to life.

1. Verify your logic using the Verify Project tool.

2. Click Download to send the program to the PLC.

3. Switch the controller to Run Mode.

4. Test your program by toggling inputs or using a connected HMI or pushbuttons.

Safety Reminder: Always test programs in a controlled, non-production environment before deploying.

 Conclusion: Start Small, Scale Fast

Learning to program Allen-Bradley PLCs opens the door to a rewarding and future-proof career in automation. By starting with basic ladder logic and progressing through real-world examples, you can build the confidence and skillset needed for increasingly complex systems.

Whether you’re working on a packaging line or a large manufacturing cell, this knowledge will make you a valuable asset to any automation team.

For more information, contact PLG Automation:
Email: sales@plgautomation.com
Phone: 800-906-9271