HART analog input module with differential input stage

A Highway Addressable Remote Transducer (HART) analog input module with a differential input stage, the HART analog input module comprising:

• a plurality of input stage processors each connected to one of a plurality of HART field devices to detect a DC signal and a HART communication signal from a signal superimposed with the DC signal and the HART communication signal from the corresponding HART field device and to output the detected DC signal and HART communication signal;
• a multiplexer sequentially outputting the DC signal and HART communication signal from each of the plurality of input stage processors in response to a control signal;
• an A/D conversion processor converting a DC signal of each channel sequentially output from the multiplexer to a digital signal;
• a HART modem demodulating a HART communication signal of each channel sequentially output from the multiplexer;
• and
• a controller providing the control signal to the multiplexer and processing the digital signal output from the A/D conversion processor and the demodulated HART communication signal output from the HART modem.