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Allen-Bradley's Micro800 family sits between simple relay replacements and full Logix-platform PLCs. With six models spanning from a fixed 12-I/O brick to an 84-I/O expandable powerhouse, there's a Micro800 for nearly every standalone machine — but choosing the wrong one means paying for features you don't need or running out of capacity mid-project.
This guide breaks down each model, compares them side by side, and helps you decide when to stay with Micro800 and when to step up to CompactLogix.
The Micro800 family at a glance
All Micro800 controllers share the 2080 catalog prefix and are programmed with Connected Components Workbench (CCW) — Rockwell's free software that supports Ladder Diagram, Function Block Diagram, and Structured Text. That alone makes Micro800 attractive for OEMs: no annual software license fees.
Here is how the six models stack up:
| Feature | Micro810 | Micro820 | Micro830 | Micro850 | Micro870 | Micro880 |
|---|---|---|---|---|---|---|
| Embedded I/O | 12 (8 DI / 4 DO) | 12–20 | 10–48 | 24–48 | 12–24 | 12–24 |
| Expansion I/O Modules | None | Up to 3 | Up to 3 | Up to 5 | Up to 8 | Up to 8 |
| Max Total I/O | 12 | ~36 | ~72 | ~88 | ~76 | ~76 |
| User Memory | 2 KB | 20 KB | 20 KB | 64 KB | 100 KB | 100 KB |
| Data Logging | No | No | No | No | Yes (SD card) | Yes (SD card) |
| EtherNet/IP | No | Yes (built-in) | No | Yes (built-in) | Yes (built-in) | Yes (built-in) |
| Serial Port | Yes (RS-232) | Yes (RS-232/485) | Yes (RS-232/485) | Yes (RS-232/485) | Yes (RS-232/485) | Yes (RS-232/485) |
| Modbus TCP | No | Yes | No | Yes | Yes | Yes |
| Motion Control | No | No | No | No | No | Up to 3 axes (PWM/PTO) |
| PID Control | No | Yes | Yes | Yes | Yes | Yes |
| Power Supply | 24V DC | 24V DC / 120V AC | 24V DC / 120V AC | 24V DC / 120V AC | 24V DC | 24V DC |
| Programming Languages | LD, FBD | LD, FBD, ST | LD, FBD, ST | LD, FBD, ST | LD, FBD, ST | LD, FBD, ST |
| Approximate CPU Cost | $100–$150 | $200–$400 | $200–$350 | $400–$700 | $500–$800 | $600–$1,000 |
Key takeaway: The Micro810 and Micro830 are stripped-down models without Ethernet. The Micro820 is the entry point for networked control. The Micro850 brings more memory and I/O expansion. The Micro870 and Micro880 add data logging and, in the Micro880's case, basic motion control.
Connected Components Workbench: free programming software
Every Micro800 controller is programmed with Connected Components Workbench (CCW), which Rockwell Automation offers as a free download. This is a significant cost advantage over the Logix platform, where Studio 5000 licenses start at several thousand dollars.
CCW supports three IEC 61131-3 languages:
- Ladder Diagram (LD) — available on all models, familiar to anyone who's programmed a MicroLogix or SLC 500
- Function Block Diagram (FBD) — available on all models, useful for analog signal processing and PID loops
- Structured Text (ST) — available on Micro820 and above, essential for math-heavy applications and data manipulation
CCW also integrates PanelView Component HMI configuration, so you can program your controller and design your operator interface in a single tool. For OEM machine builders shipping multiple units, this zero-license-cost toolchain can save thousands per year compared to Studio 5000 + FactoryTalk View.
When to choose each model
Micro810: simple relay replacement
The Micro810 is a fixed 12-I/O controller with no expansion, no Ethernet, and just 2 KB of memory. It's designed to replace timer/relay logic in simple machines — conveyor start/stop sequences, basic pump alternation, or lighting control. If your application needs more than a handful of hardwired I/O and some timers, skip to the Micro820.
Micro820: entry-level networked control
The Micro820 is the most popular model in the family for good reason. It includes built-in EtherNet/IP, supports Modbus TCP/RTU, handles PID loops, and allows up to 3 expansion modules. It's the ideal choice for:
- Single-machine control with HMI connectivity
- HVAC and building automation systems
- Water/wastewater pump stations
- Packaging machines with moderate I/O counts
The Micro820 with relay outputs (2080-LC20-20AWB) is a good option when you need to switch AC loads directly without external relays.
Micro830: offline applications
The Micro830 offers more embedded I/O options (up to 48 points) and 3 expansion slots, but lacks Ethernet. It's essentially a Micro820 without network connectivity. Choose it only when your application is truly standalone — no HMI, no remote monitoring, no data collection. In practice, the Micro820's Ethernet capability is worth the small price premium in almost every case.
Micro850: mid-range workhorse
The Micro850 triples the memory (64 KB vs 20 KB) and adds 2 more expansion slots (5 total vs 3). With up to 88 total I/O points, it handles larger standalone machines where the Micro820 runs out of room. Typical applications include:
- Multi-axis cutting or forming machines (I/O intensive but no CIP Motion needed)
- Process skids with 30+ analog and digital signals
- OEM machines with complex sequencing logic
Micro870: data-centric applications
The Micro870 bumps memory to 100 KB and introduces SD card data logging. The 8 expansion slots support up to 76 total I/O. Choose the Micro870 when you need on-board data recording for compliance, trending, or batch tracking — without installing a separate data logger or historian.
Micro880: motion + data
The Micro880 adds up to 3 axes of basic motion control (PWM and pulse train output) on top of the Micro870's data logging and 100 KB memory. It's the top of the Micro800 line and suits machines that need simple positioning — label applicators, indexing tables, or cut-to-length systems — without stepping up to the cost and complexity of a Logix motion controller.
Expanding Micro800 I/O capacity
Micro800 controllers use plug-in modules in the 2080 catalog series. Common expansion modules include:
- 2080-IQ4 — 8-channel 12/24V DC digital input module
- 2080-OB4 — 4-channel DC digital output module
- 2080-IF4 — 4-channel analog input (voltage/current)
- 2080-OF2 — 2-channel analog output
- 2080-MEMBAK-RTC — Memory backup with real-time clock
Modules snap directly onto the right side of the controller. No separate backplane or rack is needed — just slide, click, and configure in CCW.
Micro800 vs MicroLogix: migration path
If you're still running MicroLogix controllers (1761, 1762, 1763, 1764, or 1766 catalog series), you should know that Rockwell Automation has discontinued the entire MicroLogix product line. The Micro800 is the official replacement, but it's not a drop-in swap.
Key differences from MicroLogix
| Aspect | MicroLogix (Legacy) | Micro800 (Current) |
|---|---|---|
| Programming Software | RSLogix 500 (paid license) | CCW (free) |
| Programming Language | Ladder Diagram only | LD, FBD, Structured Text |
| Network Protocol | EtherNet/IP, DH-485, DF1 | EtherNet/IP, Modbus TCP/RTU |
| Program Conversion | — | No direct import — requires rewrite in CCW |
| I/O Wiring | 1762 expansion modules | 2080 expansion modules — different footprint |
| Status | End-of-life, limited spares | Active production, current support |
Migration tips
- Plan for a program rewrite. RSLogix 500 programs do not convert to CCW. Use this as an opportunity to clean up legacy code and adopt Structured Text for complex routines.
- Map your I/O carefully. MicroLogix 1762 expansion modules have different channel counts and wiring from 2080 modules. Create a full I/O cross-reference before ordering hardware.
- Size up one tier. If your MicroLogix 1400 (1766) was near capacity, start your Micro800 evaluation at the Micro850 or Micro870, not the Micro820.
- DH-485 is gone. If your MicroLogix communicates via DH-485, you'll need to migrate that network to EtherNet/IP or use a protocol converter.
For help decoding Allen-Bradley part numbers during your migration, see our catalog number decoder guide.
Micro800 vs CompactLogix: when to step up
The Micro800 handles standalone machine control. But there are clear signals that you've outgrown it and need a CompactLogix 5380 or 5480:
- System integration: You need the controller to participate in a plant-wide ControlLogix architecture via Produced/Consumed tags. Micro800 can't do this.
- CIP Motion: If your machine requires coordinated multi-axis servo control over EtherNet/IP, you need Logix. The Micro880's PWM/PTO motion is basic positioning only.
- Safety SIL 2/3: Micro800 has no safety-rated variant. CompactLogix offers the Compact GuardLogix 5380 for integrated safety.
- Large I/O counts: Beyond ~90 I/O points, CompactLogix with 5069 I/O modules is more practical and scalable.
- Add-On Instructions (AOIs): Studio 5000 supports AOIs for reusable, encapsulated code blocks. CCW does not.
- Redundancy: If you need controller redundancy, only ControlLogix provides it.
If none of the above apply, the Micro800 will likely do the job at a fraction of the cost — both hardware and software. For a broader look at the entire Allen-Bradley lineup, read our Allen-Bradley PLC buyer's guide.
Frequently asked questions
Can I use Micro800 controllers with Studio 5000?
No. Micro800 controllers are programmed exclusively with Connected Components Workbench (CCW). Studio 5000 is for the Logix platform — ControlLogix and CompactLogix. The good news is that CCW is completely free, while Studio 5000 requires a paid license.
What's the difference between Micro820 and Micro830?
The main difference is Ethernet connectivity. The Micro820 includes a built-in EtherNet/IP port and supports Modbus TCP, making it suitable for networked applications with HMIs and remote monitoring. The Micro830 has serial ports only (RS-232/485) and no Ethernet. Both offer the same 20 KB memory and 3 expansion slots. In most projects, the Micro820 is the better choice because network connectivity is increasingly essential.
Is there a migration tool to convert RSLogix 500 programs to CCW?
No. Rockwell does not provide an automatic conversion tool between RSLogix 500 (MicroLogix) and Connected Components Workbench (Micro800). Programs must be rewritten manually. However, the logic concepts are the same — ladder rungs, timers, counters, and math instructions all have equivalents in CCW.
Can Micro800 controllers communicate with ControlLogix and CompactLogix?
Yes, with limitations. Micro820, Micro850, Micro870, and Micro880 controllers with EtherNet/IP ports can exchange data with Logix controllers using explicit messaging (MSG instructions). However, they do not support Produced/Consumed tags, which means they cannot participate in the high-speed, implicit data exchange that Logix-to-Logix connections use.
Choose your Micro800 controller
The Micro800 family covers everything from simple relay replacement (Micro810) through data-logging and basic motion (Micro870/880), all with free programming software. Match your I/O count, memory needs, and communication requirements to the right tier.
Browse our full inventory of Allen-Bradley controllers, I/O modules, and accessories — including Micro820, Micro850, and Micro870 units ready to ship.