The SolarTemp series of instruments are mechanically robust and designed for industrial use as well as harsh environmental conditions. IP65 protection, etc. (frontal) meets these requirements. Anti-electromagnetic interference meets the requirements of applicable industry standards. After startup, the instrument performs an internal self-test and checks the function of the connected sensor. The automatic diagnostic program in the microprocessor continuously monitors the authenticity of the sensor signal so that the sensor fault signal can be sent through the display unit. The result is displayed as a message. By powering the measuring instrument through a transmitter, the solar cells are loaded only when the current loop fails, thus providing a secure, independent, local display.