Just a few years ago, when you selected an electronic control, you had a number of components that were required. There was the microprocessor-based controller with an LED display, which had a series of parameters that required programming. The control could be programmed by pressing a number of buttons until you got the set point, differential, defrost, and alarm settings.
Two temperature probes were used. One probe was for the set point to cut in and cut out the compressor. Usually, this probe was placed in the return air section. A second probe would be placed in the evaporator to determine the end temperature of a defrost cycle and maybe control fan delays.