Hardware Rating Plate; Function Principle - Siemens SITRANS TW 7NG3242 Betriebsanleitung

1.3.2

Hardware rating plate

The following figure shows an example of a hardware rating plate.
Figure 4
1.3.3

Function principle

The measuring signal supplied by a resistance transmitter (two, three or four-wire
circuit), voltage transmitter, current transmitter or thermocouple is converted into a
digital signal in an analog-digital converter (1, figure 5, page 86). This is evaluated in
a microcontroller (2) corrected according to the sensor characteristic and converted
into an output current (0/4 ... 20 mA) or an output voltage (0/2 ...10V) in a digital-ana-
log converter (5). The sensor characteristics and the data necessary for parameter-
ization of the transmitter are stored in a non-volatile memory (3).
AC and DC voltages can be used as a power supply (f). A bridge rectifier in the power
supply unit allows the power supply to be connected without paying attention to the
polarity. The device must be connected to a PE conductor for safety reasons.
The HART modem or a HART communicator enables parameterization of the
transmitter by a protocol according to the HART specification. The transmitter can be
parameterized directly at the measuring point by the HART output terminals (c).
The operating display (4) signals the undisturbed or disturbed operating state of the
transmitter. A message relay (7) enables signaling of sensor errors and / or dropping
below or exceeding of the limit value. The 0/4 ... 20 mA current can be checked with
a measuring instrument through the test jack(s) at current output.
SITRANS TW
A5E00054075-05
a
Example of a hardware rating plate
Technical Description
D-76181 Karlsruhe
0044
Hardware version
Firmware version
HART document revision
Device type
85