Hart is a Data communication Bus applied in field equipments; it is abbreviation of “Highway Addressable Remote Transducer.” It adds a current FM Signal on 4~20 mA, 1200Hz stands for Logic “1”,2200Hz stands for “0”, Baud rate 1200 bps. The signal wave is just like following:
2.Hart Field Network Map
Hart is using 4~20mA transmission cable to transfer the signals. It is very suited to be used in the field to save the communication cable. See following picture of HART Network Map:
3.Precautions to use Hart
Hart Communicator and Hart Modem should be parallel to Electromagnetic Flow meter output, no polarities on load ends.
Resistance should be more than 200Ω and less than 500Ω.
Hart Communicator, Hart Modem cannot connect in current loop in series.
Hart Communicator and Hart modem can set the electromagnetic flow meter parameters, the communication address is non-zero value, and baud rate is 4800.
If the communication, address, baud rate is not correct, Hart Communicator and Hart Modem cannot be used to set the parameters of the flow meter.