Allen-Bradley PLC programming for a Motion Axis Gear Instruction

In the world of industrial automation, Programmable Logic Controllers (PLCs) play a vital role in managing the operation of various machines and processes. One of the leading manufacturers of PLCs is Allen-Bradley, a brand owned by Rockwell Automation. This article aims to provide a helpful guide to Allen-Bradley PLC programming, specifically focusing on the Motion Axis Gear (MAG) instruction. We will explore its purpose, applications, and a step-by-step approach to implementing it effectively.

What is the Motion Axis Gear Instruction?

The Motion Axis Gear (MAG) instruction is a powerful command used in Allen-Bradley PLC programming to synchronize the motion of two axes in a coordinated manner. This instruction allows one axis (the “slave”) to follow the motion of another axis (the “master”) at a specific gear ratio. It is essential for applications requiring precise coordination between two or more motors, such as conveyor systems, robotic assembly lines, and packaging equipment.

Why Use the Motion Axis Gear Instruction?

Using the MAG instruction can improve the efficiency and precision of your automation processes.

Some benefits include:

  • Enhanced synchronization: The MAG instruction enables accurate coordination between two axes, ensuring smooth and synchronized motion.
  • Improved precision: By controlling the gear ratio, the MAG instruction allows for precise control over the relative speed and position of the slave axis.
  • Increased flexibility: The MAG instruction can be adapted for various applications, making it a versatile solution for different automation requirements.

Step-by-Step Guide to Implementing the Motion Axis Gear Instruction

Step 1: Set up the axes
Before implementing the MAG instruction, it is essential to configure the master and slave axes in the system. This includes setting up the motion groups, defining axis parameters, and assigning appropriate tags.

Step 2: Configure the MAG instruction
To use the MAG instruction, open the appropriate routine in RSLogix 5000 or Studio 5000, the software used to program Allen-Bradley PLCs. Drag and drop the “MAG” instruction from the instruction set into your ladder logic program.

Step 3: Define the instruction parameters
The MAG instruction has several parameters that need to be defined:

  • MasterAxis: This parameter specifies the master axis, which the slave axis will follow.
  • SlaveAxis: This parameter designates the slave axis, which will be geared to the master axis.
  • GearRatioNum: The numerator of the gear ratio (the ratio between the slave axis’s speed and the master axis’s speed).
  • GearRatioDenom: The denominator of the gear ratio.

Step 4: Set up the trigger condition
The MAG instruction requires a trigger condition to activate. This can be an input signal, a tag, or any other condition that suits your application. Connect the trigger condition to the input terminal of the MAG instruction.

Step 5: Test and verify
After implementing the MAG instruction, test the functionality of the axes and verify that the slave axis follows the master axis with the desired gear ratio. Adjust the parameters if needed, and troubleshoot any issues that arise.


The Motion Axis Gear instruction is a valuable tool in Allen-Bradley PLC programming for ensuring accurate synchronization and precise control between two axes. By understanding its purpose, applications, and implementation steps, you can harness the power of the MAG instruction to enhance the efficiency and flexibility of your automation systems.

PLC Programming for a Motion Axis Gear Instruction

The video below shows how to program a MAG instruction using Studio 5000

Throughout the video, I will give you a detailed reason so please watch the whole video for the best knowledge share.

I hope that with the video above, you easily picked up how to program a MAG instruction inĀ  Rockwell Automation’s Studio 5000.

I will be putting together more programming videos and articles upon request, I already have several ideas and will be starting to add more videos to my YouTube channel which is Shane Welcher

I would love to hear what you guys think so far as I am trying to get this website whipped into shape.

Drop me a comment here or on my YouTube channel.



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Motion Axis Gear instruction