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2 6 6 D D S H A R T | P R E S S U R E T R A N S M I T T E R S | O I/ 2 6 6 D D S - E N R E V. B
. . .6 Commissioning
Write protection activation via dip switch
Standard instruments do not feature the external, non intrusive
Zero, Span and Write Protection push buttons. To activate this
function it is necessary to proceed as detailed below:
• Remove instrument cover and the integrated digital LCD
display (if installed).
• On the connection board, place dip switch 4 in
"up" position.
Correcting the lower range value / zero shift
During installation of the transmitter, transmitter, zero shifts
caused by mounting (e.g., a slightly oblique mounting position
due to a remote seal, etc.) may occur; these must be corrected.
IMPORTANT
The transmitter must have reached its operating temperature
(approx. 5 min. after startup, if the transmitter has already
reached the ambient temperature) in order to perform zero
shift correction. The correction must be made at dp (or p) = 0.
IMPORTANT
The button unit must be available for this purpose Operating
the buttons using a magnetic screwdriver is not permitted
because it may generate some interferences with the magnetic
pickup system.
Set lower range value
• Apply the lower range value pressure (4 mA) from the process
or from a pressure generator on 266 DDS system, primary and
secondary units. The pressure must be stable and applied
with a high level of accuracy << 0.05 % (observing the set
damping value).
• Press the "Z" button the primary pressure transmitter for few
seconds. The output signal will be is set to 4 mA. The span will
remain unchanged.
IMPORTANT
Setting the lower range value by using the push buttons
is possible if the write protection is not enabled.
Correct the zero shift
The zero shift caused by the installation may be cancelled in
different ways:
• Pressing the "Z" button (under the identification plate on the
top of the transmitter, if present) or the "Zero" internal button
(on the connection board) for few seconds will cause the
output to go at 4 mA.
• It is also possible to align the digital PV value to zero.
To accomplish it raise the dip sw. 3 on the communication
board of primary device to the up (1) position and press the
zero button. This functionality will align the PV digital value to
0 of 266DDS and if the calibrated span it is zero based, the
output will go at 4 mA.
• Using the optional LCD with keypad ("Configuration of the
pressure transmitter using the integral LCD HMI" for further
information).
IMPORTANT
The procedure described above does not affect the physical
pressure shown; it only corrects the analog output signal.
For this reason, the analog output signal may differ from the
physical pressure (PV Value) shown on the digital display or
the communication tool. To avoid this discrepancy, correct
the zero position shift (zero shift) via the PV-BIAS/OFF-SET
functionality.
Installing/Removing the external push
buttons
• Loosen the screws that fix the nameplate plate and slide the
plate to gain access to the local adjustments.
• Loosen the push buttons assembly screws (1) holding down
the plastic element which is spring loaded.
• Remove the gasket (3) which is positioned below the
pushbutton plastic cover (2).
• The three push buttons (4) and the relevant springs (5) can
now be removed from their seat.
Figure 18 - External pushbutton assembly components
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