Smart transmitter circuit diagram with hart interface

The circuit consists of sensors, A/D converters, microcontroller AD 421 and peripheral circuits. The A/D converter AD7714 converts the 10mV analog signal sent from the sensor into a digital quantity. After being processed by the microcontroller, it is serially transmitted to the AD421 and converted into a 4~20mA current signal. The converter uses a low-pass filter and a modem to receive the HART data transmitted by the current loop, and then sends it to the UART or asynchronous serial port of the microcontroller. The HART data transmitted by the current loop is sent to the modulator by the UART or asynchronous serial port. , is coupled from the C3 pin to the output of AD421 after shaping. The coupling capacitance is determined by C3 of the AD 421.