Xylem OMNI sensus C2 User Manual page 14

Illustration 2
Illustration 2 is used for all instruments with internal pull-up resistors. The voltage
supplied by the instrument's input when not connected to any circuitry should not
exceed 24 Vdc nom. and must not exceed 30 Vdc max. Otherwise, it will overload the
MOSFET inside the OMNI+ register. The voltage supplied to the register is allowed to
be different from the instrument's supply voltage.
Ground is common for both the OMNI+ register and instrument.
Illustration 3
Illustration 3 is used for instruments without internal pull-up resistors and without optical
isolators internal to their inputs. Ground is common for both the OMNI+ register and
instrument. When the OMNI's MOSFET is open (not conductive), nearly the full voltage
supplied to the OMNI will occur at the instrument's input. It must be able to withstand
this voltage (24 VDC in Illustration 3).
*In case the instrument's input provides optical isolation, the connection shown in
Illustration 1 should be used.
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