What is the difference between CompactLogix and ControlLogix?

What are the basic features, similarities and differences between Rockwell Automation CompactLogix and ControlLogix controllers?

CompactLogix and ControlLogix are both programmable automation controllers (PACs) that are used to automate industrial processes. While both systems are widely used in automation applications, there are several key differences between the two that should be considered when selecting a PAC for a particular application.


The primary difference between CompactLogix and ControlLogix is the size of the system and the types of applications it can be used for. CompactLogix is designed for smaller applications that require fewer I/O points and less complex logic, while ControlLogix is designed for larger, more complex applications that require more I/O points and more sophisticated logic.

CompactLogix controllers have a smaller footprint and are less expensive than ControlLogix controllers, making them more suitable for smaller, simpler applications. The maximum number of I/O points and the number of control tasks that can be programmed in a CompactLogix system are also limited, making them less suitable for larger, more complex applications.


ControlLogix controllers, on the other hand, are designed for large, complex applications that require more I/O points, more control tasks and more sophisticated logic. They have a larger footprint and are more expensive than CompactLogix controllers, but they are also capable of more complex programming and more powerful data processing.

Another key difference between CompactLogix and ControlLogix is the type of programming language used. CompactLogix controllers use ladder logic, a graphical programming language, while ControlLogix controllers use a more powerful, text-based programming language called Structured Text. This makes ControlLogix controllers better suited for more complex applications that require more sophisticated programming.

Finally, CompactLogix controllers are typically limited to Ethernet communication protocols, while ControlLogix controllers can support a variety of communication protocols, including Ethernet, ControlNet, DeviceNet, and Modbus. This allows ControlLogix controllers to communicate with a much wider range of devices, making them better suited for applications that require communication with multiple devices.

In summary, CompactLogix controllers are smaller, less expensive, and better suited for simpler applications, while ControlLogix controllers are larger, more expensive, and more suitable for larger, more complex applications.