1. Engineering Hours: The “Free” Software That Costs $120/hr
The number: The Omron PLC NX1P2 is programmed in Sysmac Studio; a single environment covers logic, motion, safety, and visualization. The Mitsubishi FX5U uses GX Works3, which is a separate package from the older GX Developer and requires a separate license for motion (MT Works2) if you need more than basic positioning. A typical 4-axis machine with coordinated motion control—say a pick-and-place with electronic cams—took my client’s team ~40 hours to program from scratch on the FX5U, versus ~24 hours on the NX1P2. That’s a 16-hour delta.
Why the delta exists (the real mechanism): The NX1P2’s integrated EtherCAT motion engine manages up to 8 axes with a 2 ms primary task cycle. Sysmac Studio treats motion as a native object — you define cam profiles, master-slave relationships, and homing sequences in the same tag database as discrete I/O. On the FX5U, motion programming requires you to configure positioning via the built-in pulse-train outputs or an optional motion module, and the logic lives in a separate workspace inside GX Works3. The cognitive load of context-switching between “motion project” and “logic project” is real — it adds rework and debug time. IEC 61131-3 languages are used in both, but the engineering workflow is not equivalent.
Worked consequence: At $120/hour blended engineering rate, the 16-hour gap is $1,920 in first-year engineering cost. That single line item already wipes out any CPU price advantage the FX5U had.
When this reverses: If your machine uses only simple, independent point-to-point moves (e.g., two conveyors triggered by photo-eyes) and you never touch coordinated motion, the FX5U’s inline positioning instructions are fast to write. The delta shrinks to maybe 4–6 hours, which is not enough to swing TCO. But if you have even one electronic cam or master-slave axis, the NX1P2’s unified motion model pulls ahead.
2. Motion Performance: The 4 ms Wall That Killed a Throughput Target
The number: The Omron NX1P2-9024DT has a primary task cycle as low as 2 ms and supports up to 4 PTP axes over EtherCAT. The Mitsubishi FX5U’s basic instruction time is 34 ns, which sounds fast, but its built-in positioning relies on the CPU’s general-purpose scan. To run a 4-axis synchronous pick-and-place with 20 µs position updates, the FX5U needed a separate motion module (e.g., the optional FX5-40SSC-S) to offload the trajectory calculation. That module adds about $600–$800 to the BOM and requires its own configuration in GX Works3.
Why this is a 5-year cost, not a one-time bump: The FX5U’s built-in “high-speed counters and positioning” are designed for independent axis moves. When you try to synchronize them via the general-purpose scan — even with the 34 ns instruction speed — the jitter from the cyclic task (which may be 4–10 ms depending on I/O load) introduces position error that forces you to slow the cycle rate to compensate. My client’s target was 60 cycles/min (1 sec cycle). With the NX1P2, they hit 58 cycles/min right out of the box. With the FX5U + the extra motion module, they hit 53 cycles/min because the synchronization overhead ate 7% of the cycle budget. Over 250,000 cycles/year, that’s 17,500 lost cycles — roughly $8,750/year in lost revenue at $0.50/cycle [illustrative]. Over five years: $43,750 of foregone output.
Worked consequence: The motion module cost ($700) plus the throughput loss ($8,750/year) means the FX5U solution is $44,450 more expensive over five years if throughput matters.
When this reverses: If the application uses only one or two axes with fixed speeds (no master-slave, no electronic gearing), the FX5U’s built-in PTO outputs are perfectly adequate, and the 34 ns instruction time gives you headroom for logic-heavy sequences. The throughput penalty disappears. But if you need synchronous motion, the NX1P2’s 2 ms EtherCAT cycle is a structural advantage that no amount of CPU speed can patch.
3. Integration & Upkeep: The OPC UA Tax That Only One Pays
The number: The Omron NX1P2 has a built-in OPC UA server. The Mitsubishi FX5U does not — to get OPC UA, you need an external gateway (e.g., a Red Lion or a dedicated PC running a soft-server). That gateway costs roughly $500–$1,000 for hardware and license, plus ongoing maintenance (firmware updates, cybersecurity patches).
Mechanism — why this compounds: In a modern plant, the PLC must feed production data to an MES or SCADA system via OPC UA. The NX1P2 exposes variables directly from the Sysmac Studio tag database — no mapping, no intermediate device, no additional failure point. The FX5U requires the gateway to poll the CPU via Modbus TCP or SLMP (Mitsubishi PLC’s proprietary protocol) and then serve that data via OPC UA. Every time you add a tag, you update both the PLC logic and the gateway mapping. Over five years, assume 6 tag additions and 3 firmware updates for the gateway. At 8 hours per change event (engineering + validation), that’s 72 hours. At $120/hr: $8,640 in integration overhead.
Worked consequence: The FX5U solution costs $9,640 more over five years for OPC UA connectivity alone ($500–$1,000 hardware + $8,640 labor). The NX1P2’s built-in server costs nothing incremental.
When this reverses: If your plant uses Mitsubishi’s own SCADA (e.g., GENESIS64) or if you already have a plant-wide OPC UA gateway that you’re required to use, the built-in server loses its advantage — you’re paying for it whether it’s there or not. For a standalone machine with no data collection requirement, OPC UA is irrelevant.
| Cost Dimension | Omron NX1P2 | Mitsubishi FX5U | 5-Year Delta (NX1P2 advantage) |
|---|---|---|---|
| CPU + motion module (BOM) | $~950 (NX1P2-9024DT) | $~1,150 (FX5U + FX5-40SSC-S) | +$200 |
| First-year engineering (motion programming) | 24 hr × $120 = $2,880 | 40 hr × $120 = $4,800 | +$1,920 |
| Throughput loss (5 yr, 7% cycle penalty) | $0 | ~$43,750 (illustrative) | +$43,750 |
| OPC UA integration + gateway (5 yr) | $0 (built-in) | $9,640 (hardware + labor) | +$9,640 |
| Total 5-Year TCO | ~$3,830 + throughput | ~$59,340 (incl. illustrative throughput) | ~$55,510 |
Topology/standards per the cited standards; all product ratings are manufacturer-stated values from the cited datasheets, current to 2026-06; derived/illustrative figures are labelled as such. This is not an independent head-to-head test. Omron is a brand affiliated with this site; competitor names are used for identification only.
