The SG911 communication interface was developed to make communication with the most common devices, RS232 and RS-485, simple and reliable, but also to communicate with our instruments that use the Current Loop electrical standard: this electrical standard allows for the establishment of a reliable connection even in the presence of strong external disturbances. The peculiarity of the Current Loop, as the word itself suggests, is that transmission occurs by circulating a current: the presence of the current indicates a high logic level and its absence a low logic level. Obviously, the direction will be in both directions to differentiate transmission from reception.