Description
Mitsubishi MELSEC-Q Network Data Link Unit
Model: QJ71LP21-25 | High-Speed MELSECNET/H Communication Module
Product Overview
The genuine Mitsubishi QJ71LP21-25 is a high-performance MELSECNET/H network module engineered specifically for the MELSEC-Q series PLC platform. Made in Japan, this unit serves as a critical data link for industrial automation, facilitating ultra-high-speed, high-capacity communication between controllers and remote I/O stations. Designed for optical loop configurations, it ensures maximum noise immunity and data integrity over long distances. This module is essential for complex automation architectures requiring seamless synchronization and high-bandwidth data transmission across demanding manufacturing environments.
Technical Specifications
| Parameter | Specification Details |
|---|---|
| Brand / Origin | Mitsubishi Electric / Made in Japan |
| Catalog Number | QJ71LP21-25 |
| Network Type | MELSECNET/H (Optical Loop) |
| Transmission Speed | 25 Mbps / 10 Mbps (Selectable) |
| Max Link Points | 8192 Points (for LB/LW/LX/LY) |
| Medium Support | SI/H-PCF/QSI Optical Fiber Cable |
| Platform Support | Mitsubishi MELSEC-Q Base Units |
Key Features & Integration Benefits
- Advanced Noise Immunity: The optical fiber interface provides total isolation from electromagnetic interference (EMI), making it ideal for high-voltage industrial zones.
- Redundant Loop Architecture: Supports dual-loop wiring to maintain network continuity in the event of a single cable failure, ensuring zero downtime.
- Diagnostic LED Array: The front panel features active status indicators (RUN, ERR, MST) for rapid real-time troubleshooting and link verification.
- High-Capacity Data Sharing: Facilitates massive cyclically transmitted data between processors, essential for synchronized multi-axis control or large-scale facility monitoring.

