There are two forms of addressing for indicating the HART address. There is a short frame address of one byte and a long frame address of five bytes.

The short frame address byte is eight bits (without the start, parity, or stop bits). The first bit indicates a primary or secondary host. The second bit indicates a burst mode transmission. The third and fourth bits are always zeros and the last four bits indicate the HART address. A HART short frame address is shown in Figure 1-11.

The long frame address is composed of five bytes shown in Figure 1-12. Devices are identified with an expanded device type plus a device ID number, totaling 38 bits within the five bytes. In the first byte, bit 1 indicates a primary or secondary host and bit two indicates the burst mode. The expanded device type uses the last six bits of the first byte concatenated to the second byte (14 bits). The the last three bytes of the long frame address indicate the device ID number for the device (24 bits).