The 4-port communication combiner and converter RS4 has been designed for signal conversion between four RS232/485 serial interfaces and an Ethernet connection. All the interfaces are galvanically isolated. The set of practical options provides for an ideal choice for any communication system demanding a reliable and trouble-free operation. The converter is equipped with automated detection of communication rate ADC (“AutoDirectionCircuitry”) on all RS485 communication interfaces, significantly simplifying the system integration of the device, as the user no longer requires a program interface or any additional corrections and/or device settings after the installation in case the transmitting equipment is replaced. The RS232 communication interface is equipped with detection as well. The detection function identifies the type of final control device (data terminal, e.g. a computer): the user simply specifies on the RS2 converter whether the connected device is operating as a DTE (“Data Terminal Equipment”) unit or a DCE (“Data Circuit-Terminating Equipment”) unit. This eliminates the need for a crossover null model cable, standardising the use of unified connecting cables and removing the need for any additional interventions on the installations in case the polarisation of control unit is changed. The RS232 interfaces conform to the EIA/TIA 232 standard and support the transmission of complete information set (DCD, DSR, RD, TD, RTS, CTS, DTE and RI). The RS4 converter supports all standard RS232 (up to 116Kbps) and RS485 (up to 912Kbps) communication rates and operates on a single 12V DC voltage power supply. Also available is a variant with redundant power supply.