A transducer with a discrete output must be off when it is supposed to be off and on when it is supposed to be on.
A transducer with an analog output must accurately measure the physical quantity of interest and convert it to an electrical quantity such as voltage, current, frequency, or pulse width.
A transducer with an analog input and a digital output must accurately measure the physical quantity of interest and convert it to a digital word that can be sent over a parallel or serial interface.
I'm not sure that I answered the question you were asking, because I may have misunderstood the question.