Siemens SITRANS P - Electronics

4.4.1 Electronics
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① Measuring cell sensor ⑧ Buttons
② Measuring amplifier ⑨ Display
③ Analog-to-digital converter ⑩ Connection for external ammeter
④ Microcontroller ⑪ EEPROM
⑤ Digital-to-analog converter I
A
Output current
⑥ EEPROM U
H
Auxiliary power
⑦ HART modem
Mode of operation
●
The inlet pressure is converted into an electrical signal by the sensor ①.
●
This signal is amplified by the measuring amplifier ② and digitized in an analog-to-digital
converter ③.
● The digital signal is analyzed in a microcontroller ④ and corrected with regard to linearity
and thermal characteristics.
● The digital signal is then converted in a digital-to-analog converter ⑤ into the output current
of 4 to 20 mA.
A diode circuit provides reverse polarity protection.
Description
4.4 Functional principle
SITRANS P320/P420 with 4 to 20 mA/HART
Operating Instructions, 11/2019, A5E44852162-AC 31