Operation Of The Electronics - Siemens SITRANS P300 Operating Instructions Manual

Description
3.6 Mode of operation
3.6.2

Operation of the electronics

Description
Figure 3-5
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
I
A
U
H
The input 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. It is then converted in a digital to analog converter (5) into the
output current of 4 to 20 mA. A diode circuit provides reverse voltage protection. You can
make an uninterrupted current measurement with a low resitance ammeter at the connection
(10). The data specific to the measuring cell, the electronic data and parameter settings are
stored in two non-volatile memories (6). The first memory is linked with the measuring cell,
the second with the electronics.
The buttons (8) can be used to call up individual functions, called modes. If you have a
device with a digital display (9), you can track the mode settings and other messages on it.
The basic mode settings can be changed with a computer via the HART modem (7).
3-6
Operation of the electronics with HART communication
Measuring cell sensor
Measuring amplifier
Analog-to-digital converter
Microcontroller
Digital-to-analog converter
Each with a non-volatile memory in the measuring cell and in the electronics
HART modem
Buttons (local operation)
Digital display
Connection for external ammeter
Output current
Auxiliary power
SITRANS P300 with HART communication
Operating Instructions, 06/2005, A5E00359579-02