Allen-Bradley PLC Guide: ControlLogix vs CompactLogix vs Micro800

Allen-Bradley controllers run more factories in North America than any other PLC brand. Rockwell Automation's lineup spans three distinct platforms — ControlLogix for plant-wide control, CompactLogix for machine-level automation, and Micro800 for simple standalone applications — each with its own hardware architecture, software ecosystem, and price point.

The challenge: picking the wrong platform means either overpaying for capability you never use, or hitting performance walls that force a costly mid-project swap. Should you spec a ControlLogix for that packaging line, or will a CompactLogix handle it? When does a $180 Micro820 make more sense than a $1,200 CompactLogix? And what about all those legacy PLC-5, SLC 500, and MicroLogix systems still running in plants everywhere?

This guide covers every current Allen-Bradley control platform, compares them head to head, and lays out a decision framework based on I/O count, integration needs, safety requirements, and budget.

Allen-Bradley control platform overview

Allen-Bradley organizes its controller lineup into three tiers, each built for different scales of automation:

All three share a common philosophy — modular hardware, broad communications support, and scalable architectures — but they differ significantly in processing power, I/O density, networking capabilities, and cost.

ControlLogix (1756 series): the flagship platform

ControlLogix is Allen-Bradley's top-tier Programmable Automation Controller (PAC). Built around a chassis-based architecture, it handles everything from discrete manufacturing to continuous process control, motion, safety, and batch applications — often simultaneously in a single controller.

Key features

• Chassis-based modularity: 4, 7, 10, 13, or 17-slot chassis. Mix and match CPUs, I/O, communication, and motion modules in any slot.
• Hot-swappable modules: Replace I/O and communication modules without powering down the chassis — critical for 24/7 operations.
• Redundancy support: Controller redundancy (1756-RM2) for applications that cannot tolerate downtime.
• Integrated safety: GuardLogix controllers (1756-L7xS series) combine standard and SIL 2/SIL 3 safety control in one platform.
• High-performance motion: Supports up to 256 CIP motion axes via SERCOS or EtherNet/IP.
• Multi-discipline control: Sequential, process, motion, drives, and safety — all in one controller with one programming environment.

Current CPU lineup

When to choose ControlLogix

• Applications exceeding 5,000 I/O points
• Requirements for controller redundancy or hot standby
• Multi-discipline control (process + motion + safety in one controller)
• Plant-wide EtherNet/IP backbone with hundreds of nodes
• Industries with strict uptime requirements: oil & gas, power generation, water treatment, automotive

Browse our ControlLogix 1756 inventory →

CompactLogix (5069 / 1769 series): the mid-range platform

CompactLogix delivers most of the power of ControlLogix in a smaller, more cost-effective package. It uses the same Studio 5000 programming environment and the same instruction set, so engineers can move between platforms without retraining.

CompactLogix 5380 (current generation, 5069 platform)

The 5380 controllers represent the latest CompactLogix generation, offering significantly improved performance and security over the prior 5370 generation.

• Controllers: 5069-L306ERM through 5069-L350ERM (standard), 5069-L310ERS2 through 5069-L340ERMS2 (safety)
• User memory: 0.6–10 MB standard, 0.3–5 MB safety
• Dual Gigabit Ethernet ports supporting DLR, linear, and star topologies
• Up to 31 local 5069 Compact I/O modules
• Integrated motion: Up to 256 CIP motion axes (controller-dependent)
• CIP Security: TLS/DTLS encryption for controller-to-device communications

CompactLogix 5480 (edge + standard control)

The 5480 platform is unique — it combines a Logix real-time controller with a Windows 10 IoT Enterprise operating system in a single device. This means you can run standard Logix control programs alongside Windows applications (SCADA, analytics, custom apps) without a separate PC.

• Models: 5069-L406ERMW through 5069-L4200ERMW
• Use case: Edge computing, local data analytics, machine learning at the controller level
• Same Compact 5069 I/O compatibility as 5380

CompactLogix 5370 (prior generation, 1769 platform)

Still widely deployed and fully supported:

• Controllers: 1769-L16ER through 1769-L36ERM
• Uses 1769 Compact I/O modules (different form factor from 5069)
• Dual EtherNet/IP ports (100 Mbps)
• Good choice when: budget is tight, 1769 I/O is already standardized in your facility, or application fits within 5370 performance limits

When to choose CompactLogix

• Standalone machines or cell-level control with 500–5,000 I/O points
• Need Logix-class programming without ControlLogix chassis cost
• OEM machines shipping in volume (compact footprint, lower BOM cost)
• Applications requiring integrated safety (Compact GuardLogix)
• Edge computing requirements (5480 specifically)

Browse our CompactLogix inventory →

Micro800 (2080 series): the compact option

The Micro800 family targets applications where a full Logix controller is overkill. Programmed with the free Connected Components Workbench (CCW) software, these controllers offer a low-cost entry point to Allen-Bradley automation.

Micro800 model comparison

When to choose Micro800

• Budget-sensitive applications under 100 I/O points
• Standalone machines that do not need to integrate into a Logix architecture
• Replacing legacy relay logic or simple timer/counter circuits
• Applications where free programming software (CCW) is a deciding factor
• OEM volume machines where per-unit controller cost matters most

Browse our Micro800 controllers →

Head-to-head: ControlLogix vs CompactLogix vs Micro800

Legacy platforms: what to do with PLC-5, SLC 500, and MicroLogix

If your facility still runs PLC-5 (1771), SLC 500 (1747/1746), or MicroLogix (1761/1762/1763/1764/1766) controllers, you are on borrowed time. Rockwell Automation has discontinued these platforms, and replacement parts are getting harder to find and more expensive every year.

Recommended migration paths

We stock genuine replacement parts for all legacy platforms — SLC 500 modules, 1746 I/O, MicroLogix 1200, and more — so you can keep your existing systems running while you plan and execute migrations.

For detailed migration guidance, see our dedicated guides:

• PLC-5 to ControlLogix Migration: Which 1756 Module Replaces Your Legacy Part?
• SLC 500 to CompactLogix Migration: Step-by-Step Replacement Guide

How to choose: a decision framework

Use this quick decision tree to narrow down the right platform:

1. Is the application standalone with fewer than ~100 I/O? → Start with Micro800.
2. Do you need integration with a Logix-based plant network? → Move to CompactLogix (even for small I/O counts, the Logix ecosystem benefits may justify the cost).
3. More than 5,000 I/O, or need redundancy/SIL 3 safety? → ControlLogix is your platform.
4. OEM machine builder shipping volume? → CompactLogix 5380 for Logix integration, Micro850/870 for cost-sensitive standalone machines.
5. Edge computing or local analytics needed? → CompactLogix 5480 (Windows + Logix in one box).

Related resources

• Allen-Bradley Catalog Number Decoder: How to Read 1756, 2080, 5069 Part Numbers
• Allen-Bradley 1756 Major Fault Codes: Quick Diagnosis Guide
• CompactLogix 5380 vs 5480: Which Controller Do You Need?
• Micro800 Series Guide: Micro810 vs Micro820 vs Micro850
• Allen-Bradley 5069 Compact I/O: Complete Module Selection Guide
• Allen-Bradley PowerFlex VFD Selection Guide: 525 vs 753 vs 755
• Siemens S7-1500 Complete Buyer's Guide: CPUs, I/O Modules & Accessories
• Honeywell Burner Control Replacement Guide: RM7800, RM7840 & EC7800

Frequently asked questions

What is the difference between a PLC and a PAC?

A Programmable Logic Controller (PLC) traditionally handles discrete logic — relay replacement, sequencing, and basic I/O control. A Programmable Automation Controller (PAC), like the ControlLogix and CompactLogix, extends this with multi-discipline capabilities: process control, motion, safety, and advanced data handling in a single controller. Allen-Bradley's Logix platform blurs the line — it is technically a PAC but universally called a PLC in the field.

Can I mix ControlLogix and CompactLogix in the same plant?

Yes. Both use Studio 5000 and communicate natively over EtherNet/IP. A common architecture uses ControlLogix as the plant-level or area controller, with CompactLogix at each machine or cell. They share tags and produce/consume data seamlessly over the network.

Is the Micro800 compatible with Studio 5000?

No. The Micro800 family uses Connected Components Workbench (CCW), which is a separate and free programming environment. Micro800 controllers can communicate with Logix controllers over EtherNet/IP using Modbus TCP or explicit messaging, but they are not part of the Logix ecosystem. If you need tight integration with a Logix architecture, choose CompactLogix instead.

How long will Rockwell support the SLC 500 and MicroLogix?

Rockwell Automation has discontinued manufacturing of PLC-5, SLC 500, and MicroLogix controllers. While replacement parts are still available through distributors like us, support is limited to break/fix — no firmware updates or new features. Rockwell strongly recommends migrating to the Logix or Micro800 platforms. The longer you wait, the harder and more expensive spare parts become.

What programming languages do Allen-Bradley controllers support?

Studio 5000 (ControlLogix and CompactLogix) supports Ladder Diagram, Function Block Diagram, Structured Text, and Sequential Function Chart. CCW (Micro800) supports Ladder Diagram, Function Block Diagram, and Structured Text. All Allen-Bradley controllers support Ladder Diagram, which remains the most widely used language in North American manufacturing.