The SSE HART Modem allows for interfacing to Instruments utilising the HART Protocol. Using this protocol allows for more data to be extracted from the Instrument i.e. in the case of a flow meter - forward flow, reverse flow, totalised flow, etc
The HART Communication Protocol is an industrial automation protocol and its most notable advantage is that it can communicate over standard 4-20 mA analogue instrumentation current loops, sharing the pair of wires used by the analogue signal.
The 4 -20mA signal can still be used to obtain the main value i.e flow rate, pressure, etc.