Three Levels of Automation from Mitsubishi Electric
Mitsubishi Electric is one of the most respected industrial automation manufacturers in the world. Their programmable logic controller (PLC) lineup covers three fundamentally different device classes: the compact smart relay Alpha2, the mid-range FX5U, and the modular flagship platform iQ-R. The right choice depends on the scale of the task, budget, and communication requirements.
Alpha2 — Smart Relay for Small-Scale Tasks
The Alpha2 series is not a full-featured PLC but a programmable smart relay with a fixed I/O count (up to 30 I/O). It targets simple applications: lighting control, pump stations, ventilation, and small conveyors. Programming is done via a graphical function block editor directly on the device display or through AL-PCS/WIN software — no knowledge of IEC 61131-3 languages is required. The Alpha2's strengths are low cost and easy installation; its limitations are restricted communication options and no native Ethernet/IP support.
FX5U — The Go-To Choice for Mid-Range Applications
The FX5U series is the current mainstream compact PLC from Mitsubishi. The base unit features a built-in 100 Mbps Ethernet port and supports SLMP, CC-Link IE Field Basic, and Modbus TCP protocols. I/O can be expanded from 32 to 256 points using expansion modules. Program memory is 64K steps — sufficient for most mid-complexity tasks. The full set of IEC 61131-3 languages is supported within the GX Works3 environment. The FX5U is ideal for controlling production lines, packaging machines, water supply systems, and HVAC. It is the most common choice when replacing legacy FX3U controllers.
iQ-R — Modular Platform for Complex Systems
The iQ-R platform is designed for large distributed automation systems. CPU modules support up to 16,384 I/O and feature built-in Ethernet with CC-Link IE TSN (time-sensitive networking). Specialized CPUs are available: Motion CPU for multi-axis control, Safety CPU for functional safety applications, and a C-language CPU for custom processing. Instruction cycle time starts at 0.98 µs. The iQ-R is deployed in automotive manufacturing, semiconductor production, large-scale energy facilities, and complex transportation systems.
Series Comparison Table
| Specification | Alpha2 | FX5U | iQ-R |
|---|---|---|---|
| Max I/O points | 30 | 256 | 16,384 |
| Program memory | ~2K steps | 64K steps | up to 4 MB |
| Built-in Ethernet | No | 100 Mbps | 1 Gbps |
| Communication protocols | RS-232/RS-485 | Modbus TCP, SLMP, CC-Link IE Field Basic | CC-Link IE TSN, Modbus, PROFINET, OPC UA |
| IEC 61131-3 languages | FBD (limited) | LD, FBD, ST, SFC, IL | LD, FBD, ST, SFC, IL + C |
| Programming environment | AL-PCS/WIN | GX Works3 | GX Works3 |
| Typical applications | Lighting, pumps, HVAC | Production lines, packaging, HVAC | Automotive, semiconductor, energy |
GX Works3 Programming Environment
GX Works3 is the unified development environment for both FX5U and iQ-R. It supports all five IEC 61131-3 languages, includes a built-in simulator for testing logic without physical hardware, and integrates with the Motion Control system for drive synchronization. Key advantages include structured program organization with reusable libraries, project version control, and advanced real-time diagnostics. GX Works3 is free for basic use; a full license is required for advanced Motion and Safety functions.
Competitor Comparison: Delta DVP and Siemens S7-1200
In the compact PLC segment, the FX5U competes primarily with the Delta DVP/AS series and the Siemens S7-1200. Delta offers a lower price point and wide availability, but falls short of Mitsubishi in documentation quality and advanced protocol support. The Siemens S7-1200 has a more powerful TIA Portal ecosystem and better SCADA integration, but comes at a higher cost and requires more skilled personnel. The FX5U sits squarely in the middle: competitive pricing, Japanese manufacturing reliability, and compatibility with a broad range of expansion modules.
Application Areas for Mitsubishi PLCs
Mitsubishi controllers are widely used across industries: food and pharmaceutical manufacturing (FX5U, iQ-R), machine building and CNC machining (FX5U with Motion CPU or iQ-R), water supply and wastewater treatment (Alpha2, FX5U), and automotive production (iQ-R). Paired with Mitsubishi MR-J series servo drives, the iQ-R platform delivers synchronized multi-axis control with microsecond precision. For variable frequency drive control applications, browse our PLC catalog to find the right model for your project.
Conclusion
The Mitsubishi Electric lineup covers the full spectrum of industrial automation tasks — from simple Alpha2 smart relays to the powerful modular iQ-R platform. For most mid-level production tasks, the FX5U remains the optimal choice thanks to its balance of price, functionality, and reliability. Check availability and pricing for Mitsubishi PLCs in our catalog.
