In this article is done a review of the HART (Highway Addressable Remote Transducer) protocol with special emphasis on his performance in different conditions of operation. Besides the protocol basic characteristics, analyzes the operation form of the medium access mechanism and his effects on the performance with only one master, two masters, a burst mode device or combinations of these; the theoretical analysis is contrasted with data obtained in the laboratory. Finally are made several comments about the future of HART protocol in the automation concert.