The SHT-12 FS radio transmitter allows remote control of up to 4 functions of a radio module or receiver from the SH-12 radio series. With the new fixed transmitter SHT-12 FS, switching signals from relay contacts, push buttons, or switches are transmitted without the need for installation of control lines. It features 4 inputs for potential-free contacts. For each of the 4 inputs, the mode of operation for pulse or switching signal transmission can be set separately. In pulse signal transmission, the transmission duration corresponds to the contact duration, and the radio link remains occupied while the signal is active. In switching signal transmission, a radio signal is only transmitted when there is a change in state at the input, thus preventing the radio link from being permanently blocked. A blue LED indicates the transmission operation. It not only represents transmitted radio signals but also provides information about the quality of radio communication and the transmitter's supply voltage. The red LED indicates, depending on the wiring at the radio receiver, either the status of the receiver's supply voltage or the input of the receiver confirmation. An integrated buzzer also acoustically signals the confirmation from the receiver. If the confirmation is disabled, every change in the input state is reported instead. The radio transmitters of the SH-12 series operate with extremely low interference due to their special transmission characteristics. With interference-resistant radio transmission and extremely short reaction times, ranges of over 1000 m can be achieved. For strong narrowband interference or the use of multiple parallel radio systems, the operating frequency can be adjusted to individual needs. The SH-12 radio series can be operated in both unidirectional and bidirectional modes. In bidirectional communication, the transmitter automatically adjusts its transmission behavior according to the quality of the radio link. The transmitters are factory-programmed with a continuous serial number.