2 | Product and functional description
FISCHER Mess- und Regeltechnik GmbH
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BA_EN_DE85
2 Product and functional description
2.1 Delivery scope
• Differential pressure transmitter DE85 ECO-LINE
®
version as stated on the type plate
• Operating Manual
• Closing screw for degree of protection IP65
2.2 Function diagram
Sensor
Display
Analogue output
Differential pressure
Power supply
24 V AC/DC
RS485
Modbus
µC
DIP-switch
Configuration
Zero-point buttons
Offset correction
Auxiliary
energy
Fig. 1:
Function diagram
2.3 Design and mode of operation
The device is based on a piezo-resistive sensor element that is suitable for
measuring overpressure, under-pressure and differential pressure. The pres-
sures to be compared have a direct effect on a silicon membrane equipped with
a measuring bridge.
When the pressure is equal, the measuring membrane is in its idle state. If a
pressure difference occurs, the membrane is deflected and a resistance change
takes place on the attached measuring bridge. This change is evaluated by the
device's electronics and transformed into the an analogue output signal with a
rising or falling characteristic curve. The output signal can also be dampened
and square rooted.
• Alternatively, the device is available as a 2-wire or Modbus RTU variant.
• All versions can be equipped with a full-graphic LC display.
In total, the device can be supplied in the following configurations.
3-wire
2-wire
Modbus
RTU
Analogue output
0/4 … 20 mA or 0/2 … 10 V, switchable
x
Current loop 4 … 20 mA
x
RS485 Modbus RTU
x
Options:
Full graphic LC display
x
x
x
