The QJ71GP21S-SX is Mitsubishi Electric’s CC-Link IE Controller Network master/local module for the MELSEC-Q programmable controller series using multimode optical fibre transmission — providing 1 Gbps deterministic inter-PLC communication for distributed MELSEC-Q control architectures within the same building or facility complex, where the 550 m maximum station-to-station distance of multimode fibre is sufficient and the lower installation cost of multimode fibre components compared to single-mode offers a practical economic advantage over the QJ71GP21-SX. As the multimode fibre variant of the CC-Link IE Controller Network module family, the QJ71GP21S-SX is the standard specification for large-scale intra-facility PLC communication networks where multiple MELSEC-Q controllers in different production areas must exchange process data continuously and deterministically. Atlantech Drives holds stock of the QJ71GP21S-SX. Contact us for fast worldwide delivery and competitive pricing.
What Is the QJ71GP21S-SX?
The QJ71GP21S-SX is a MELSEC-Q series intelligent communication module implementing CC-Link IE Controller Network over multimode optical fibre (50/125 µm OM3 or OM4, LC connector). It is electrically and functionally identical to the QJ71GP21-SX single-mode module — both operate at 1 Gbps, support up to 120 stations per ring, share the same cyclic link data capacity (LB: 16,384 points, LW: 8,192 points), and use the same GX Works2 configuration interface. The sole difference is the fibre type and resulting maximum cable distance: the QJ71GP21S-SX supports up to 550 m between adjacent stations using OM3/OM4 multimode fibre, while the QJ71GP21-SX supports up to 10 km using single-mode fibre. The multimode LC connector on the QJ71GP21S-SX is physically distinguishable from the single-mode variant by the beige/ivory connector body colour versus the blue colour of single-mode LC connectors — an important visual check when maintaining mixed-fibre-type installations.
Key Technical Specifications
- Model: QJ71GP21S-SX
- Network: CC-Link IE Controller Network
- Transmission Speed: 1 Gbps
- Transmission Medium: Multimode optical fibre, 50/125 µm (LC connector)
- Maximum Station-to-Station Distance: 550 m (OM3/OM4 multimode fibre)
- Maximum Stations per Network: 120
- Cyclic Data Capacity: LB: 16,384 points; LW: 8,192 points
- Transient Data: Supported (up to 960 bytes per request)
- Topology: Ring (dual loop for redundancy)
- Network Redundancy: Automatic loop-back on single cable fault
- Current Consumption (5 VDC internal bus): 0.90 A
- Operating Temperature: 0°C to 55°C
- Compatible CPUs: All MELSEC-Q Universal model and H-model CPUs
- Weight: Approx. 0.30 kg
Typical Industrial Applications
The QJ71GP21S-SX is the standard CC-Link IE Controller Network module for large-scale intra-facility automation architectures. In automotive body shop automation, the QJ71GP21S-SX connects MELSEC-Q controllers governing individual welding stations, transfer line segments, and quality inspection gates on a single CC-Link IE Controller Network ring — enabling each station controller to monitor the production status of upstream and downstream stations in real time without point-to-point communication programming. The ring network’s automatic fault recovery (loop-back within 0.5 seconds on single cable fault) ensures that a cable cut between two stations does not halt the entire production line. In petrochemical plant distributed control systems, multiple MELSEC-Q controllers managing different process units (distillation, reaction, separation) are connected via QJ71GP21S-SX networks to share process variable data for cascade control and plant-wide material balance calculations, replacing the slower serial communication links used in legacy MELSEC-A installations. Steel rolling mill automation uses the QJ71GP21S-SX to synchronise speed references between the multiple MELSEC-Q drive controllers governing successive rolling stands — the 1 Gbps network speed and deterministic cyclic refresh ensure that speed reference data propagates between stations within a single scan cycle, maintaining the precise speed ratios required for defect-free strip thickness control.