Exploring the Contrast Between CompactLogix and ControlLogix PLCs

CompactLogix, ControlLogix, industrial automation, PLCs, Rockwell Automation
April 11, 2024

Rockwell Automation is a leading brand in industrial automation, offering a diverse range of products catering from small PLCs to large IoT modules. Rockwell's PLCs are renowned for their robust hardware architecture and user-friendly programming software. Among the popular PLCs with large I/O capability are CompactLogix and ControlLogix. In this article, we will delve into the dissimilarities between CompactLogix and ControlLogix PLC brands.

ControlLogix vs CompactLogix

CompactLogix is categorized by Rockwell as a small control system, while ControlLogix is classified as a large control system. This distinction implies that ControlLogix possesses more advanced IO handling, memory, and other software features tailored for large control systems compared to CompactLogix PLC.

PLC Model Numbers

CompactLogix 5370 – starting with the 1769 series
CompactLogix 5380 – starting with the 5069 series
CompactLogix 5480 – starting with the 5069 series
ControlLogix 5570 – starting with the 1756 series
ControlLogix 5580 – starting with the 1756 series

Memory Capacity

ControlLogix boasts a maximum memory capacity of 40MB, while CompactLogix reaches up to 20MB.

Number Of Embedded Ethernet Ports

ControlLogix can have a maximum of two embedded Ethernet ports, whereas CompactLogix supports up to three embedded Ethernet ports.

Redundancy

ControlLogix offers redundancy capabilities, which are absent in CompactLogix PLC. Thus, systems requiring redundancy must utilize ControlLogix PLC.

Display System

ControlLogix features a display system providing diagnostic and troubleshooting data. In contrast, CompactLogix PLC troubleshooting is primarily through LEDs. Consequently, ControlLogix offers enhanced diagnostic viewing capabilities.

Communication Protocols Supported

ControlLogix supports Ethernet/IP, ControlNet, DeviceNet, Remote I/O, SyncLink, and USB. On the other hand, CompactLogix supports EthernetI/P, USB, and DeviceNet.

Sercos Motion Support

ControlLogix PLC supports the Sercos motion communication standard, widely used in machine automation projects, a feature not available in CompactLogix PLC.

I/O Points Support

ControlLogix PLC supports a maximum of 128,000 digital and 4,000 analog IOs, surpassing CompactLogix PLC.

Integrated Displayport

CompactLogix PLC integrates a display port enabling connection to industrial monitors with high definition, a feature absent in ControlLogix PLC.

Conclusion

While ControlLogix PLC has inherent advantages due to its large-system capabilities, both PLCs offer numerous similar features suitable for harsh, critical, and large industrial environments. Thus, the choice between CompactLogix and ControlLogix depends on specific project requirements and scalability needs.