The MR-J4-10B is Mitsubishi Electric’s 100 W MELSERVO-J4 series servo amplifier for 200 V single-phase or three-phase AC power supply with SSCNET III/H optical fibre network interface — the entry-level model in the MR-J4-B SSCNET III/H sub-series, providing closed-loop servo control at continuous rated output current of 1.1 A for Mitsubishi HG-KR and HG-MR series small-frame servo motors in precision multi-axis machine tool, semiconductor equipment, and electronic assembly automation where low-power axes must be synchronised via high-speed fibre optic servo network. In stock at Atlantech Drives. Request your quote within 24-48 hours with worldwide shipping and 12-month warranty.
What Is the MR-J4-10B?
The MR-J4-10B is a MELSERVO-J4 series servo amplifier providing 100 W (0.1 kW) continuous output power via SSCNET III/H — Mitsubishi’s 150 Mbps full-duplex optical fibre servo communication network — receiving position commands from a MELSEC-Q motion controller (Q17nDSCPU, Q172DSCPU), MELSEC iQ-R motion module (RD77MS), or FX3U-20SSC-H adapter at 0.888 ms communication cycle time. The «B» suffix designates the SSCNET III/H network variant as distinct from the «A» pulse train input variant — the MR-J4-10B receives all position commands, speed commands, and parameter data exclusively via SSCNET III/H optical fibre, with no pulse train input terminals. This network-only command architecture provides deterministic position command delivery independent of host controller scan time, enabling tighter multi-axis synchronisation than pulse train systems can achieve. The MR-J4-10B accepts servo motors with the 22-bit multi-turn absolute encoder standard across all MR-J4 series amplifiers, eliminating the power-up homing requirement that incremental encoder systems need. The compact housing (40 mm width) enables dense multi-axis installation in the MELSERVO-J4 series’ common bus wiring configuration, where multiple MR-J4-B amplifiers share AC power input and regenerative resistor connections via dedicated power junction connectors.
Key Technical Specifications
- Model: MR-J4-10B
- Rated Output Power: 100 W (0.1 kW)
- Power Supply: 200–240 VAC single-phase or three-phase, 50/60 Hz
- Continuous Output Current: 1.1 A
- Maximum Output Current: 3.3 A (3× continuous peak)
- Compatible Servo Motors: HG-KR053, HG-KR13, HG-MR053, HG-MR13 and equivalent
- Command Interface: SSCNET III/H optical fibre (150 Mbps full-duplex)
- Communication Cycle: 0.444 ms or 0.888 ms (selectable)
- Encoder Interface: Serial 22-bit absolute encoder (262,144 pulses/rev)
- Safety Function: STO (Safe Torque Off), IEC 61800-5-2
- Regenerative Brake: Built-in
- Housing Width: 40 mm
- Operating Temperature: 0°C to 55°C
- Dimensions (W × H × D): 40 mm × 150 mm × 138 mm
- Weight: Approx. 0.8 kg
Compatibility & System Integration
The MR-J4-10B connects to SSCNET III/H motion controllers via plastic optical fibre (POF) patch cables — the amplifier’s CN1A (input from controller or previous amplifier) and CN1B (output to next amplifier) ports form a daisy-chain ring, with the motion controller managing all amplifiers in the chain as a single coordinated servo system. Compatible SSCNET III/H motion controllers include the MELSEC-Q Q172DSCPU and Q173DSCPU motion CPUs (up to 32 and 96 axes respectively), the MELSEC iQ-R RD77MS motion module (up to 16 axes), and the FX3U-20SSC-H adapter (up to 2 axes from an FX3U base unit). In a mixed-power multi-axis system, the MR-J4-10B can share the same SSCNET III/H chain with higher-power MR-J4-B amplifiers (MR-J4-20B, MR-J4-70B, MR-J4-500B, etc.) — all MR-J4-B variants use identical SSCNET III/H communication regardless of power rating, enabling a single motion controller to manage axes ranging from 100 W to 22 kW on the same network. The MR-J4-10B is also compatible with the MELSEC iQ-R RD77GF CC-Link IE Field Network motion module, which connects via an MR-J4-GF-RJ interface, though for direct SSCNET III/H the RD77MS is the appropriate controller. The MR-J4-10B’s parameter settings are configured via MR Configurator2 connected via USB to the amplifier, or remotely via the motion controller’s engineering software (GX Works3 with MT Developer2 for Q-series motion, GX Works3 for iQ-R motion).
Expert Tips
When commissioning an MR-J4-10B in a multi-axis SSCNET III/H chain, verify the optical fibre connections before applying power — the POF connectors use a push-pull locking mechanism, and a partially inserted connector causes the amplifier to report a SSCNET III/H communication error (AL.9F or equivalent) that can be misdiagnosed as an amplifier fault. Inspect the POF connector endface for contamination using a fibre inspection scope before insertion — even a fingerprint on the plastic fibre endface can increase optical insertion loss sufficiently to cause intermittent communication errors at 150 Mbps. For the MR-J4-10B’s servo tuning, note that 100 W motors typically have very low rotor inertia — the load inertia ratio (load inertia ÷ motor inertia) for a direct-coupled 100 W motor can be very high even with light loads, which can cause instability if the servo response (bandwidth) is set too high. Start auto-tuning at a low response level (response level 3–5 in MR Configurator2) and increase incrementally, monitoring for oscillation at each level. For multi-axis systems with many MR-J4-10B amplifiers sharing a common AC power rail, calculate the total inrush current at system power-up — the soft-start circuits in multiple MR-J4-10B amplifiers charging simultaneously can generate substantial inrush current that trips upstream circuit protection. Use a power sequencing relay to delay the main power contactor closure for 0.5–1 second after the control power is applied, allowing the amplifier control circuits to initialise before the power stage charges.
Frequently Asked Questions
Q: Can the MR-J4-10B operate as a standalone servo amplifier without a SSCNET III/H motion controller connected?
A: No. The MR-J4-10B receives all position and speed commands exclusively via SSCNET III/H — it has no pulse train input or analogue command input. Without a connected SSCNET III/H motion controller, the MR-J4-10B cannot execute position moves. For standalone operation (test bench, simple jog control), a minimal SSCNET III/H controller such as the FX3U-20SSC-H (2-axis) or a MELSEC iQ-R RD77MS4 (4-axis) must be connected. Alternatively, MR Configurator2’s JOG operation function can command the motor via USB without a motion controller for basic commissioning and test purposes.
Q: Does the MR-J4-10B support fully closed-loop control with a separate load-side linear encoder?
A: Yes. The MR-J4-10B supports a dual encoder configuration — the motor’s built-in 22-bit absolute encoder provides the primary velocity feedback for the current and speed loops, while a separate linear or rotary encoder on the load side connects to the CN2L connector for position loop feedback. This fully closed-loop architecture eliminates positioning errors caused by ball screw backlash, thermal expansion, and mechanical compliance between the motor and load. The dual encoder option requires the motion controller to be configured for fully closed-loop mode in the servo parameter settings.
Q: What is the maximum number of MR-J4-10B amplifiers that can be connected in a single SSCNET III/H chain?
A: The maximum number of amplifiers per SSCNET III/H chain is determined by the motion controller’s axis limit — the Q172DSCPU supports up to 32 axes, the Q173DSCPU up to 96 axes, and the RD77MS up to 16 axes per module. Each MR-J4-10B occupies one axis in the chain. The SSCNET III/H physical chain supports up to 16 amplifiers between the controller and the chain terminator on most motion controllers, with longer chains requiring daisy-chain extension. Verify the specific motion controller’s maximum chain length in its hardware manual.
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