The Modbus module in an IP65 housing with 4 digital inputs and 2 relay outputs with manual control level was developed for decentralized switching tasks. Suitable for e.g. accommodating light switches and window contacts in a room and switching two strip lights or as a blind control. 2 motor-operated fire dampers can also be controlled. The relay contacts must be protected by suitable load-dependent measures. The inputs must be connected to potential-free contacts. The inputs and outputs can be switched and queried via standard registers using a Modbus master. The module address, bit rate and parity are set using two rotary switches. Bit rate and parity are also set using software.