Hart circuit and method for determining the state of a field interface thereof

A Highway Addressable Remote Transducer (HART) circuit, comprising:

• a control interface, an adjustable power supply module, a first HART module, an isolation module, and a field interface;
• wherein the first HART module is connected to the control interface, and the first HART module is configured to generate a first control signal when receiving a first inquiry signal inputted from the control interface;
• wherein the adjustable power supply module is connected to the control interface and the first HART module, and the adjustable power supply module is configured to output a first power signal to the control interface and, and in response to the first control signal, modulate the first power signal into a first HART signal;
• wherein a first terminal of the isolation module is connected to the control interface, and the isolation module is configured to isolate a signal from the first terminal of the isolation module to generate an isolated signal and couple the isolated signal to a second terminal of the isolation module;
• and
• wherein the field interface is connected to the second terminal of the isolation module.