Complete Guide to Allen-Bradley PLCs by Rockwell Automation
Key Takeaway
Allen-Bradley is Rockwell Automation's brand of industrial programmable logic controllers (PLCs). Their product line includes ControlLogix, CompactLogix, MicroLogix, and Micro800 controllers programmed using Studio 5000 Logix Designer. Allen-Bradley PLCs are widely used in oil and gas, manufacturing, water treatment, and building automation.
Quick Answer
Allen-Bradley is Rockwell Automation's brand of industrial programmable logic controllers (PLCs). Their product line includes ControlLogix, CompactLogix, MicroLogix, and Micro800 controllers programmed using Studio 5000 Logix Designer. Allen-Bradley PLCs are widely used in oil and gas, manufacturing, water treatment, and building automation.
What Is Allen-Bradley?
Allen-Bradley is the automation hardware brand of Rockwell Automation, headquartered in Milwaukee, Wisconsin. The Allen-Bradley name traces back to 1903 and is one of the most recognized brands in industrial control. Rockwell Automation manufactures the controllers, I/O modules, drives, HMIs, and networking infrastructure that make up the Allen-Bradley ecosystem. In North America, Allen-Bradley is the dominant PLC platform — the majority of control panels in Texas oilfields, water treatment plants, and manufacturing facilities contain Allen-Bradley hardware.
PLC Family Overview
ControlLogix
ControlLogix is the flagship platform for large-scale industrial control. It uses a modular backplane chassis (1756 series) that supports multiple processors, redundant power supplies, and a wide range of I/O modules. ControlLogix is used in applications requiring high I/O count, controller redundancy, and advanced motion control — pipeline compressor stations, large manufacturing lines, and power generation facilities.
CompactLogix
CompactLogix integrates the processor and I/O in a more compact form factor using the 1769 and 5069 series hardware. It shares the same programming environment (Studio 5000) and instruction set as ControlLogix, making code portable between platforms. CompactLogix is the most common Allen-Bradley controller in oil and gas production automation — wellsite panels, tank batteries, and small pump stations where the full ControlLogix chassis is unnecessary.
MicroLogix
MicroLogix (1100, 1400) is a legacy small PLC platform programmed with RSLogix 500. While still operational in many installed systems, MicroLogix has been discontinued in favor of the Micro800 series. RSLogix 500 uses a different instruction set and addressing scheme from Studio 5000, so programs are not directly portable.
Micro800
Micro800 (Micro820, Micro830, Micro850, Micro870, Micro880) is the entry-level platform for standalone machine control and small automation systems. It is programmed with Connected Components Workbench (CCW), a free software package from Rockwell Automation. Micro800 is positioned for OEMs and simple applications that do not require the full Studio 5000 ecosystem.
GuardLogix
GuardLogix is a safety-rated variant of ControlLogix that provides SIL 2 (Safety Integrity Level 2) and SIL 3 safety functions within the same controller. It combines standard control and safety control in a single program, eliminating the need for separate safety relays and safety PLCs in many applications.
Programming Software
- Studio 5000 Logix Designer — The primary programming environment for ControlLogix, CompactLogix, and GuardLogix. Supports Ladder Diagram, Structured Text, Function Block Diagram, and Sequential Function Chart.
- RSLogix 500 — Legacy programming software for MicroLogix and SLC 500 controllers. Still widely used for maintaining existing installations.
- Connected Components Workbench (CCW) — Free programming software for Micro800 series controllers. Supports Ladder Diagram, Function Block Diagram, and Structured Text.
Supported Programming Languages
Studio 5000 supports all four IEC 61131-3 programming languages:
- Ladder Diagram (LD) — The most common language, based on relay logic diagrams. Preferred for discrete I/O control, motor circuits, and interlocks.
- Structured Text (ST) — A high-level text language similar to Pascal. Preferred for math-heavy calculations, data manipulation, and complex algorithms.
- Function Block Diagram (FBD) — A graphical language using interconnected blocks. Preferred for continuous process control, PID loops, and analog signal flow.
- Sequential Function Chart (SFC) — A graphical language for defining sequential processes with steps, transitions, and parallel branches. Used for batch processes and multi-step machine sequences.
EtherNet/IP and Device Communication
EtherNet/IP is Rockwell Automation's industrial Ethernet protocol, managed by ODVA. It runs on standard Ethernet hardware and uses TCP/IP and UDP for real-time I/O data exchange and messaging. Allen-Bradley PLCs communicate with remote I/O racks, variable frequency drives, HMI panels, and third-party devices over EtherNet/IP. Other supported protocols include DeviceNet, ControlNet, and serial DF1. Third-party SCADA platforms like Ignition connect to Allen-Bradley PLCs using native EtherNet/IP drivers without requiring RSLinx.
Allen-Bradley in Oil and Gas and Industrial Automation
Allen-Bradley PLCs are the most commonly deployed controllers in North American oil and gas operations. Common applications include:
- Wellsite automation — CompactLogix controlling rod pump controllers, plunger lift systems, and artificial lift optimization
- Tank battery control — Level monitoring, LACT unit measurement, and truck loading automation
- Compressor station control — ControlLogix managing multi-unit compressor packages with vibration monitoring and surge control
- Water treatment — Chemical feed control, filter backwash sequencing, and distribution pump management
- Manufacturing — Assembly line control, material handling, and packaging machine automation
Getting Started
New to Allen-Bradley? Follow these guides in order:
- What Is Allen-Bradley? Platform Introduction
- Getting Started with Studio 5000 Logix Designer
- Ladder Logic Programming Basics
- EtherNet/IP Device Configuration
- RSLinx Classic Setup and Driver Configuration
Sub-Article Index
Explore the full Allen-Bradley PLC knowledge cluster:
- What Is Allen-Bradley? Introduction to Rockwell Automation PLCs
- Getting Started with Studio 5000 Logix Designer
- Ladder Logic Basics — Contacts, Coils, Timers, and Counters
- Structured Text Programming — Syntax and Examples
- Function Block Diagram (FBD) Programming
- Add-On Instructions (AOI) — Reusable PLC Logic
- EtherNet/IP Device Configuration
- PID Loop Configuration — PIDE Instruction Guide
- RSLinx Classic Setup and Driver Configuration
- Fault Finding and Diagnostics
Frequently Asked Questions
Allen-Bradley is Rockwell Automation's brand of industrial PLCs, I/O modules, drives, and HMIs. The product line includes ControlLogix, CompactLogix, MicroLogix, Micro800, and GuardLogix controllers used in oil and gas, manufacturing, and utility automation.
ControlLogix uses a modular backplane chassis supporting multiple processors and I/O modules with high scalability. CompactLogix integrates the processor and I/O in a more compact form factor suited to smaller systems with lower I/O counts.
Studio 5000 Logix Designer is used for ControlLogix and CompactLogix. RSLogix 500 is used for legacy MicroLogix controllers. Connected Components Workbench is used for Micro800 series.
Studio 5000 supports all four IEC 61131-3 languages: Ladder Diagram, Structured Text, Function Block Diagram, and Sequential Function Chart. Each routine in a project can use a different language.
Yes. Allen-Bradley PLCs dominate the North American oilfield market. CompactLogix is the most common controller in wellsite panels, tank batteries, and pump stations across the Permian Basin and Eagle Ford.