US Patent 10963412 Flexible expandable automation device with hot-swappable I/O-units

A flexible expandable automation device includes: a main control unit; and at least two I/O-units connected to the main control unit and to each other via an I/O-bus. The I/O-bus works according to a daisy-chain technique. The I/O-bus has a bus signal line and a daisy-chain-control-line. Each I/O-unit has a daisy-chain-control-IN-port for receiving a daisy-chain-control-signal as a daisy-chain-control-IN-signal and a daisy-chain-control-OUT port for delivering the daisy-chain-control-signal as a daisy-chain-control-OUT-signal to a next adjacent I/O-unit. Each I/O-unit has an I/O-module carrier and a pluggable and unpluggable I/O-module. The daisy-chain-control-IN-port and the daisy-chain-control-OUT-port are part of the I/O-module carrier. Each I/O-module-carrier has a hot-swap-control unit that, in case of an unplugged I/O-module creating an interrupted daisy chain, automatically bridges the interrupted daisy chain.