The digital to analogl converter is an Electronic device which combines a digital signal with an analog value. It is most commonly used with a ADC Device to send up to 4 digital signals through a single Copper Wire. The blue pin is the analog output, the opposite pin is an (optional) analog input. A high or low signal to the third pin toggles a 0 or 1 of the respective bit in the analog output. You can rotate the device and configure which bit is toggled using a Spanner.