The Q26UDVCPU is Mitsubishi Electric’s maximum-capacity Universal V model CPU for the MELSEC-Q programmable controller series, offering 26,000 steps of program memory — 30% more than the Q20UDVCPU — while retaining the same 1.0 ns execution speed, dual built-in Ethernet and USB interfaces, and multi-CPU support that define the Universal V model family. As the ceiling of the V model range, the Q26UDVCPU is designed for the most complex standalone machine control applications where program size approaches the upper limit of what a non-memory-expandable CPU can accommodate, before the application necessitates a step up to the Universal Enhanced High-speed family. Available now at Atlantech Drives with worldwide express delivery and 12-month warranty — complete our quote form for pricing and availability.
What Is the Q26UDVCPU?
The Q26UDVCPU is the highest-capacity member of Mitsubishi Electric’s MELSEC-Q Universal V model CPU sub-family, providing 26,000 program steps in the same compact module form factor shared by all MELSEC-Q Universal CPUs. It supports multi-CPU configurations with up to four CPUs per base unit, making it suitable for systems combining sequence control with dedicated motion or process control modules. Like all Universal V model CPUs, the Q26UDVCPU does not support program memory extension via SRAM memory card or hot-standby redundant CPU configurations — applications requiring either of these capabilities should specify the Q26UDEHCPU from the Universal Enhanced High-speed family. The Q26UDVCPU is programmed using GX Works2 or GX Works3 and is fully compatible with the complete range of MELSEC-Q base units (Q3B through Q312B) and all MELSEC-Q peripheral modules including I/O, analogue, communication, and positioning modules.
Key Technical Specifications
- Model: Q26UDVCPU
- Series: MELSEC-Q Universal V model
- Program Memory: 26,000 steps
- Execution Speed: 1.0 ns per LD instruction
- I/O Points: Up to 4,096 (local)
- Built-in Interfaces: Ethernet (100BASE-TX), USB (mini-B)
- Number of Mountable Modules: Up to 64 per base
- Multi-CPU Configuration: Supported (up to 4 CPUs per base)
- Power Supply Voltage: 5 VDC (via base unit)
- Operating Temperature: 0°C to 55°C
- Weight: Approx. 0.17 kg
- Compatible Base Units: Q3B, Q5B, Q6B, Q12B, Q25B, Q32B, Q33B, Q35B, Q38B, Q312B
- Programming Software: GX Works2, GX Works3
Architecture & Design Overview
The Q26UDVCPU implements the same fourth-generation MELSEC-Q CPU architecture as all Universal model CPUs, with independent internal buses for program execution, I/O refresh, and communication processing. This separation ensures that Ethernet communication traffic — whether SLMP polling from a SCADA host, MC protocol data requests from a GOT2000 HMI, or HTTP data logging to an MES — does not introduce latency into the main scan cycle. The CPU’s 26,000-step program memory is allocated as a single contiguous block, supporting both sequence programs and SFC (Sequential Function Chart) programs within the same memory space. Device memory includes standard M, D, T, C, and Z registers at full MELSEC-Q Universal model capacity. The built-in USB port provides a direct programming interface for GX Works2 and GX Works3 without requiring an Ethernet connection, which is particularly useful during initial commissioning when the plant network may not yet be available. Inter-CPU communication in multi-CPU configurations is handled via dedicated shared memory registers, with up to 8,192 words exchangeable per scan cycle between the Q26UDVCPU and co-installed motion or process CPUs.
Expert Tips
When specifying the Q26UDVCPU for a new project, calculate the expected compiled program size in GX Works2 with all function block instances fully instantiated before finalising the CPU selection — FB libraries for motion interfaces, communication protocols, and PID control can each consume 500 to 1,500 steps per instance. A project that appears to fit within 26,000 steps at the design stage may approach or exceed the limit after full FB instantiation across multiple machine zones. If the estimated program size after full FB instantiation exceeds 22,000 steps, specify the Q26UDEHCPU instead to allow for future program expansion via SRAM memory card. For multi-CPU systems using the Q26UDVCPU alongside a QD77MS servo network module, configure the inter-CPU refresh parameters in GX Works2’s multi-CPU setting editor to transfer only the axis status and command registers that the sequence CPU actually needs — transferring the full QD77MS device map unnecessarily increases the inter-CPU communication load and extends the effective scan time of both CPUs.
Frequently Asked Questions
Q: What is the key difference between the Q26UDVCPU and the Q26UDEHCPU for a system that only needs 26,000 steps?
A: For a system with a stable program that will never exceed 26,000 steps and does not require hot-standby redundancy, both CPUs deliver identical runtime performance at 1.0 ns per LD instruction. The Q26UDEHCPU is justified when the program may grow beyond 26,000 steps in the future (expandable to 260,000 steps with an SRAM memory card), when high-availability redundancy is required, or when the system will use extension base units beyond the standard Q model configuration. For cost-controlled OEM machine designs with defined programs, the Q26UDVCPU is the more economical choice.
Q: Can the Q26UDVCPU be used as a drop-in replacement for the Q25HCPU?
A: Yes, with the standard Universal model migration considerations. The Q26UDVCPU is physically and electrically compatible with all MELSEC-Q base units that previously housed a Q25HCPU. The program should be re-verified in GX Works2 after substitution, special relay and register references checked against the Universal model migration guide, and any QJ71E71-100 Ethernet module previously used for the Q25HCPU can be removed since the Q26UDVCPU has Ethernet built in.
Q: Does the Q26UDVCPU support online program change while the machine is running?
A: Yes. Online program change (OPC) is fully supported from GX Works2 and GX Works3. Ladder rungs, SFC steps, and FB instances can be modified and written to the CPU while it is in RUN mode, with changes applied at the end of the current scan cycle. The total compiled program size after any OPC operation must remain within the 26,000-step limit.
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