Mitsubishi A6BR10 MELSECNET/10 Repeater Module
The Mitsubishi A6BR10 is a MELSECNET/10 network repeater module designed for the MELSEC A series programmable logic controller family. This module serves to extend the physical limitations of the MELSECNET/10 coaxial bus network, allowing the connection of additional remote I/O stations and extending the overall cable length. The A6BR10 is a network accessory device rather than an I/O module, and it plays a critical role in larger A series control systems where network segmentation or distance extension is required.
Network Specifications and Performance
The A6BR10 is designed for use with the MELSECNET/10 network, a proprietary factory automation network developed by Mitsubishi Electric. The network operates at a communication speed of 10 Mbps using coaxial cable as the transmission medium. The repeater module regenerates the network signal to overcome signal attenuation and dispersion, enabling the network to maintain error‑free communication over longer distances than would otherwise be possible. The A6BR10 is compatible with both the A series PLC and the QnA series PLC systems.
Cable Types and Distance Extension
The repeater module is designed to work with RG‑58A/U or Belden 9907 coaxial cables for the backbone trunk line. The maximum distance between stations on a single segment without a repeater is limited by the network's electrical characteristics and the cable type in use. The A6BR10 repeater allows the trunk line to be extended by an additional 300 meters, and multiple repeaters can be cascaded to reach distances up to 1.5 km for the entire network. The module also supports the use of 5C‑2V and 5C‑FB coaxial cables when configured appropriately.
Error Detection and Status Indicators
The A6BR10 includes diagnostic LEDs that provide visual indication of network health. The ERR1 LED illuminates when the A6BR10 detects an abnormal communication condition, such as loss of power to a segment or a cable fault. The ERR2 LED is illuminated during normal operation, indicating that the module is functioning correctly and that the network is properly terminated and operational. These LEDs allow maintenance personnel to verify network integrity at a glance without requiring specialized network diagnostic equipment.
Installation and Network Topology
When installing the A6BR10, the module is mounted in a standard A series PLC rack or backplane, taking power from the rack's bus rather than requiring a separate power supply. The coaxial cables for the incoming and outgoing network segments connect to the module via BNC connectors. For the network to operate correctly, each end of the trunk line must be terminated with 50 ohm terminators to prevent signal reflections. The repeater counts as a station on the network and consumes one node address from the total allowable station count.
Compatibility with Other Network Components
The A6BR10 is compatible with other MELSECNET/10 network components including the A1SJ71QLR21, A1SJ71QLR21‑L, and A1SJ71QBR11 master and remote I/O modules. The network supports up to 32 stations per trunk line segment when no repeaters are used, and up to 64 total stations when repeaters are properly deployed. Remote I/O stations can be distributed over extended distances, making the network suitable for large plants where control cabinets are separated by significant distances.
Power Supply and Current Consumption
The A6BR10 draws its operating power from the A series backplane, requiring 24 V DC from the rack's power supply module. The current consumption is modest, allowing the module to be powered by standard A series power supplies without exceeding their rated capacity. The module does not require any external 24 V supply beyond the rack power.
Applications and Typical Use Cases
The A6BR10 is typically used in large factories where the MELSECNET/10 network spans multiple buildings or widely separated production areas. The repeater allows remote I/O racks to be placed up to 500 meters from the master station, supporting distributed control architectures. Common applications include automotive assembly plants with multiple welding and assembly cells, material handling systems with conveyors spanning long distances, and process plants where control I/O is distributed across a large physical area. The network's deterministic communication timing ensures consistent data exchange even when repeaters are present, making it suitable for real‑time control applications.
Product Status and Legacy Support
The A series PLC platform has been largely superseded by the Q series and later the L series and iQ‑R series from Mitsubishi Electric. The A6BR10 is a legacy product that is no longer in active production, but it remains in service in many existing installations. Spare and replacement units are available through aftermarket suppliers. For new network designs, Mitsubishi recommends using the more modern MELSECNET/H or CC‑Link IE Field networks, which offer higher speed, longer distances, and simpler cabling.
