In this paper, we propose and experimentally demonstrate a network switch to improve scalability and fault tolerance for a ring network applied to articulated robots. A ring network is suitable as a network for a robot with slim joints because it can reduce the number of wires. However, it is difficult to implement when the connection state changes during operation, such as a cable break due to unexpected trouble or addition of nodes. Proposed network switch can dynamically reconfigure the ring network based on the connection status. By combining this network switch with a previously proposed network protocol which performs in low latency and high efficiency, we realize a more practical design that solves the issues of scalability and fault tolerance in current ring networks.