Hart Modem Schematics

How to use DS8500HART modem in the course is controlled

Summary: How note of this application has been introduced to use DS8500 HART modem in the course is controlled. This text discusses the connections of DS8500 and little controller and 4- 20mA electric current ring, so as to ensure correct HART communication.

Foreword

Has note of this application recommended being used in HART? DS8500 form chip modem of communication, this text should use with DS8500 data materials. Different application may require different parameter indexes, the reference that this text introduces is designed and just used in a basic example of the control circuit of course.

HART summary

The high speed can seek the long-range sensor HART of location Communication is used in digital signal transmission extensively, superpose on the analog signal of 4- 20mA electric current ring. HART agreement moves the key continuously frequently and accuses of FSK on the basis of the phase place Technology. 0 of bit is modulated in 2200Hz sine signal, 1 of bit is modulated in 1200Hz sine signal, the Potter rate is 1200bps. These two pieces of frequency can be superposed to the electric current of simulation and surrounded on signals very easily, the analog signal range is: Flow to 10Hz continuously, will not influence other signals. The unique advantage of HART agreement makes it can transmit simulation and digital signal in the same circuit.

DS8500 HART modem

DS8500 is that one is used in HART modem that course controls, offers the FSK modulation of the continuous phase place and demodulates. This low consumption modem with abundant function totally meets one layer of norms of physics that HART communication foundation presumed. DS8500 has a great deal of functions, makes users design the course control system with demodulation function of the HART modulation conveniently, high-efficiently.

The reliable signal is detected and examined

Few outside component

The sine outputs signals

Low consumption

Standard 3.6864MHz crystal

Dispose the digital signal and deal with the reliable FSK_IN signal of technical support to detect and examine; The few outside component is used for drawing HART signal out from the noise. FSK_OUT is a sine signal, it is distorted to produce the lowest harmonic wave in the system.

Fig. 1 shows for DS8500 block diagram of the principle of top floor in the intellectual changer is employed. Design and stress that has shown the interface between HART modem and peripheral IC.

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