What Is Allen-Bradley? Introduction to Rockwell Automation PLCs

Quick Answer

Allen-Bradley is Rockwell Automation's brand of industrial PLCs and automation hardware. The product line spans from entry-level Micro800 controllers to enterprise-scale ControlLogix systems with redundancy and high I/O counts, all supported by Studio 5000 or dedicated programming software.

History of Allen-Bradley and Rockwell Automation

Allen-Bradley was founded in 1903 in Milwaukee, Wisconsin, manufacturing motor starters and rheostats. The company became a pioneer in programmable logic controllers in the 1970s and 1980s with the PLC-2 and PLC-5 families. Rockwell International acquired Allen-Bradley in 1985, and the automation division was later spun off as Rockwell Automation in 2001. Today, Rockwell Automation is the world's largest company dedicated to industrial automation, with Allen-Bradley as its primary hardware brand.

PLC Product Family Breakdown

ControlLogix (1756 Series)

The ControlLogix platform is designed for large, complex applications. Key characteristics:

• Modular backplane chassis (4, 7, 10, 13, 17 slot options)
• Multiple processors per chassis for partitioned control
• Controller redundancy with automatic failover (1756-RM2)
• Up to 120,000+ I/O points per controller
• Motion control for up to 256 axes
• Best for: compressor stations, large processing facilities, pipeline control centers, and manufacturing lines

CompactLogix (1769 / 5069 Series)

CompactLogix delivers ControlLogix-class programming in a smaller footprint:

• Integrated processor with built-in EtherNet/IP ports
• 1769 (legacy) and 5069 (current) I/O form factors
• Same Studio 5000 programming environment and instruction set
• Code portability between CompactLogix and ControlLogix
• Best for: wellsite automation, tank batteries, pump stations, small water treatment plants, and OEM machines

MicroLogix (1100, 1400)

MicroLogix is a legacy small PLC platform:

• Fixed I/O with limited expansion
• Programmed with RSLogix 500 (different instruction set)
• Discontinued — replaced by Micro800 series
• Still widely installed and maintained in existing systems

Micro800 (820, 830, 850, 870, 880)

The Micro800 series targets entry-level and OEM applications:

• Programmed with Connected Components Workbench (free software)
• Plug-in modules for communications, I/O expansion, and storage
• No RSLinx required — direct USB or Ethernet connection
• Best for: standalone machines, simple pump controls, HVAC, and small building automation

GuardLogix (1756-L7SP, 5069-L3100ERMS2)

GuardLogix adds safety-rated control to the ControlLogix and CompactLogix platforms:

• SIL 2 and SIL 3 safety certification (IEC 61508)
• Integrated standard and safety control in one program
• Safety I/O modules for E-stop, light curtains, and safety interlocks
• Eliminates the need for separate safety relay systems in many applications

Choosing the Right Platform by Application Size

• Under 20 I/O — Micro800 with CCW
• 20-200 I/O — CompactLogix 5380/5480
• 200-2000 I/O — CompactLogix 5380 or ControlLogix
• 2000+ I/O or redundancy required — ControlLogix
• Safety functions required — GuardLogix

Allen-Bradley vs Siemens vs Mitsubishi

Allen-Bradley dominates North America due to integrator availability and parts supply chain. Siemens (S7-1200, S7-1500) is the leading platform in Europe and is gaining share in North American process industries due to cost advantages and TIA Portal engineering tools. Mitsubishi (MELSEC iQ-R, iQ-F) is dominant in Asia-Pacific and common in automotive manufacturing globally. All three platforms are technically capable — the best choice depends on geographic support, existing infrastructure, and integrator expertise.

Typical Industries

• Oil and gas — Wellsite control, pipeline monitoring, compressor management, tank farm automation
• Manufacturing — Assembly lines, material handling, packaging, and quality inspection
• Water and wastewater — Treatment plant control, distribution pump stations, lift station automation
• HVAC and building automation — Chiller plants, air handling units, and building management systems