P/N: 974153 |
Rev: 072016
|
ECO: 46503
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From lab to production,
providing a window into the process
-9-
1.6 TRANSMITTER PRINCIPLES OF OPERATION
The mechanical system consists of a gaged diaphragm. One side of the diaphragm is in direct contact
with the fluid media (gas or liquid) while a strain gage element in the configuration of a Wheatstone
bridge is bonded to the backside.
The deflection of the diaphragm causes a change in the resistance of the strain gage and hence a change
in the balance of the bridge. The amount of imbalance is directly proportional to the applied pressure.
This completes the translation of pressure applied to the diaphragm into a usable electrical signal.
The low level output signal from the bridge is amplified via an instrumentation amp circuit. The
amplified signal then goes to the input of the analog-to-digital (A/D) converter.
Once the microprocessor has the converted voltage input from the A/D converter, the digital signal is
sent to a digital-to-analog (D/A) converter which modulates the current of the unit’s power supply
between 4 and 20 mA for an output current proportional to the applied pressure.
Figure 1-1 Block Diagram of Operation
