The UNICOMM interface modules allow HART®-capable field devices to be interfaced with the processing controller computer. A link is possible via USB channels, an RS485 line, or by Bluetooth®. UNICOMM HART® modems are applicable not only for NIVELCO transmitters but also for all HART®-capable transmitters using standard HART® communication. The device is galvanically isolated from both sides: USB and HART®. When used as a HART®−USB modem connected to the USB of a PC, the modem does not need to be connected to an external power supply. The UNICOMM SAK−305 modules can be connected to an appropriate device input of the RS485 interface to be used as a HART® RS485 modem. Here, the communication protocol will be HART® on the RS485 line. In this case, it is necessary to use an external power supply. Ex variants can be connected with transmitters located in risky areas.