HT12E is an integrated circuit of 212 series of encoders. They are paired with 212 string of decoders for use. It's principally used in interfacing infrared circuits and RF. The preferred pair of encoder/decoder must have same number of addresses and data structure.
In other words, HT12E transforms the inputs into output that is serial. It frees the 12 bit parallel data into serial for transmission.
HT12E includes a transmission license pin that's active. The are transmitted together with the header bits through an RF or an infrared transmission medium when a trigger signal is obtained on TE snare. HT12E starts a 4-word transmission cycle upon receipt of a transmission enable. This cycle is repeated as long as TE is maintained low. As soon as TE returns to high, its cycle is completed by the encoder output and then quits.