Master - Slave Token Passing (<b>MSTP</b>) is most commonly used to connect field devices to controllers / routers / control applications. The physical layer uses RS485 which allows up to 128 devices to be installed on a single network. | Master - Slave Token Passing (<b>MSTP</b>) is most commonly used to connect field devices to controllers / routers / control applications. The physical layer uses RS485 which allows up to 128 devices to be installed on a single network. |