Mitsubishi PLC — from smart relay to modular controller
Mitsubishi Electric produces three controller lineups that cover the full spectrum of automation tasks: from lighting control in a building entrance to managing a conveyor line with dozens of axes. Alpha2 is essentially a smart relay with 14-24 I/O points and graphical programming. FX5U (iQ-F series) is a compact PLC with up to 128,000 program steps and built-in Ethernet. iQ-R is an industrial-grade modular platform for large distributed systems.
We have been working with Mitsubishi for 8 years and see a clear pattern: Alpha2 goes into small standalone facilities, FX5U handles 80% of manufacturing tasks, and iQ-R is for when you need performance and scale. Let us break down each series.
Alpha2: smart relay for small projects
Alpha2 is not a classic PLC — it is a programmable relay. 200 function blocks, 38 built-in functions, an integrated clock/calendar with 1,200 on/off commands. For tasks like "turn on ventilation at 8:00, turn off at 18:00, monitor temperature" — you do not need more.
- Models: AL2-14MR (8 DI + 6 DO), AL2-24MR (14 DI + 10 DO)
- Analog inputs: 8 channels 0-10 V (9-bit, 20 mV step) — on the base unit
- Expansion: up to 18 I/O with AL2-4EX module
- High-speed counter: 2 points, 1 kHz
- Power supply: 100-240 V AC or 24 V DC (depending on variant)
- Dimensions: 124.6 x 90 x 52 mm
Programming uses the free AL-PCS/WIN-E software. Logic is built from ready-made function blocks (timers, comparators, counters, PID). IEC 61131-3 languages are not available here — only an FBD-like editor. Engineers accustomed to Ladder Diagram may find this inconvenient, but electricians often find it more intuitive.
Alpha2 is commonly installed on small pump stations, ventilation systems, gate and barrier automation. Where a full PLC is overkill, but a simple timer relay is not enough.
FX5U (iQ-F): the workhorse for manufacturing
FX5U is the most popular Mitsubishi series on the Ukrainian market. The reasons are solid: 128k steps of program memory, built-in Ethernet, SD card for data storage, analog I/O without additional modules (on some models), and performance that noticeably exceeds the older FX3U series.
| Parameter | FX5U-32M | FX5U-64M | FX5U-80M |
|---|---|---|---|
| Digital I/O (base) | 32 (16DI+16DO) | 64 (32DI+32DO) | 80 (40DI+40DO) |
| Program memory | 128k steps | 128k steps | 128k steps |
| Speed (LD) | 34 ns/step | 34 ns/step | 34 ns/step |
| Built-in Ethernet | Yes | Yes | Yes |
| SD card | Yes | Yes | Yes |
| Max I/O (expanded) | 512 | 512 | 512 |
What makes FX5U attractive for us as integrators is the out-of-the-box compatibility with GOT2000 panels over Ethernet. No adapters, converters, or extra communication modules needed. Plug in the cable — it works.
FX5U is programmed in GX Works3, which supports all five IEC 61131-3 languages: LD, FBD, ST, IL, and SFC. For those accustomed to Structured Text, this is a serious advantage over controllers that only offer Ladder.
- Positioning: up to 4 axes, 200 kHz per channel
- Analog: FX5-4AD, FX5-4DA modules (16-bit)
- Communication: Ethernet, RS-485 (Modbus), CC-Link IE Field Basic
- Safety: built-in Safety CPU (FX5-80SSC-S)
Typical applications: packaging lines, automated warehouses, servo drive control (MR-JE/MR-J4), CNC machines. Compared to Delta DVP SV2, FX5U wins on memory and speed, but costs noticeably more.
iQ-R: modular platform for large systems
iQ-R is a completely different class of equipment. A modular rack-mount controller where you assemble the configuration from separate cards: CPU, power supply, I/O, communications, Motion, Safety. For projects with hundreds of I/O points and strict cycle time requirements.
- CPU: from R04 (40k steps, 3.92 ns) to R120 (1,200k steps, 0.98 ns)
- Max I/O: up to 4,096 points per CPU
- Networks: CC-Link IE TSN, Ethernet/IP, Profinet, Modbus TCP
- Motion: up to 32 synchronized axes
- Hot swap: I/O modules without stopping the system
- Redundancy: CPU duplication for critical processes
iQ-R is chosen for large-scale manufacturing: automotive, food processing, chemical industry. Where downtime is expensive and the system must run 24/7 without interruption.
Programming uses GX Works3 (same as FX5U, but with additional Motion and Safety modules). You can mix different CPU types in a single chassis: standard PLC + Motion CPU + Safety CPU.
Series comparison: Alpha2 vs FX5U vs iQ-R
| Parameter | Alpha2 | FX5U | iQ-R |
|---|---|---|---|
| Type | Smart relay | Compact PLC | Modular PLC |
| Program | 200 blocks | 128k steps | up to 1,200k steps |
| Performance | ~ms range | 34 ns/step | 0.98 ns/step |
| Max I/O | 18 | 512 | 4,096 |
| Ethernet | No | Yes | Yes (TSN) |
| Languages | FBD-like | LD/FBD/ST/IL/SFC | LD/FBD/ST/IL/SFC |
| Motion | No | Up to 4 axes | Up to 32 axes |
| Price range | $100-200 | $400-1,500 | $2,000-15,000+ |
Between Alpha2 and FX5U there is a capability chasm. Between FX5U and iQ-R the difference is scale and speed. If your project has fewer than 50 I/O points and does not require Motion — FX5U covers it. If you need over 200 I/O or axis synchronization — iQ-R.
Connecting Mitsubishi PLCs to peripherals
Each series has its own communication toolkit. Alpha2 works only through wired connections (discrete I/O). FX5U offers Ethernet + RS-485, enabling networks with sensors, VFDs, and HMI panels. iQ-R supports CC-Link IE TSN industrial networks with deterministic data delivery.
- Alpha2 + sensors: connection via discrete inputs or 0-10 V analog
- FX5U + VFD: RS-485 Modbus or CC-Link IE Field Basic
- FX5U + HMI: Ethernet directly (GOT2000 series)
- iQ-R + distributed system: CC-Link IE TSN up to 128 stations
For communicating with equipment from other manufacturers (Delta, Siemens), all series except Alpha2 support Modbus RTU/TCP. Protocol details are in our article on Modbus RTU and TCP for PLCs.
Compare Mitsubishi with other manufacturers: Delta DVP review or Siemens S7-1200 PLCs.
Frequently Asked Questions
What is the difference between Alpha2 and FX5U?
Alpha2 is a programmable relay with 14-24 I/O points and 200 function blocks. FX5U is a full PLC with 128k-step programs, Ethernet, all IEC 61131-3 languages, and expansion to 512 I/O. Alpha2 is for simple standalone tasks; FX5U is for production lines.
Can Mitsubishi FX5U be programmed in Structured Text?
Yes. GX Works3 supports five IEC 61131-3 languages, including Structured Text. This is convenient for complex mathematical calculations, recipe handling, and array processing.
How much does a basic Mitsubishi FX5U setup cost?
The FX5U-32MR/ES (32 I/O, relay output) costs approximately $500-700 depending on the supplier. Add an analog input module ($200-300) and an HMI panel ($400-800) — and you have a basic automation system for $1,100-1,800.
What applications suit the iQ-R?
iQ-R is chosen for large distributed systems with hundreds of I/O points, Motion tasks (up to 32 axes), and reliability requirements (hot-swap modules, CPU redundancy). Typical industries: automotive, food processing, chemical manufacturing.
Are FX3U expansion modules compatible with FX5U?
Not directly, but Mitsubishi offers the FX5-C32E adapter for connecting legacy FX3U/FX2N modules to the FX5U bus. This allows gradual migration without replacing all peripherals at once.
Choosing the right series for your project
Three series — three complexity levels. Alpha2 for "set and forget" tasks, FX5U for serious manufacturing, iQ-R for large distributed systems. 80% of our customers land on FX5U — and for good reason, as this series covers the widest range of tasks at a reasonable price.
Browse the Mitsubishi PLC catalog with prices and availability. Need expansion modules? There is a dedicated catalog section.
