Write Protect; Correcting The Lower Range Value / Zero Shift; Set Lower Range Value; Correct The Zero Shift - ABB 266 HART Operating Instruction

Write Protection
Write protection prevents the configuration data from being
overwritten by unauthorized users. If write protection is enabled,
the "Z" and "S" buttons are disabled. However, it is still possible
to read out the configuration data using the graphical user
interface (DTM) or another, similar communication tool. The
control unit may be leaded if required.
Write protection is activated as follows (also refer to the symbols
on the plate):
– First, use a suitable screwdriver to press the switch down fully.
– Then turn the switch clockwise by 90°.
Important
To deactivate the switch, push it down slightly and then turn
counterclockwise by 90°.

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 transducer. The pressure must be stable and
applied with a high level of accuracy << 0.05 % (observing the set damping value).
– Press the "Z" button on the pressure transmitter for few seconds. The output signal will be is set to 4 mA. The span will remain
unchanged.
Important
A lower range value set using this method will be stored in the non-volatile memory < 25 s (HART), when the "Z" button is pressed

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) 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 to the up (1) position and press the external zero button.
This functionality will align the PV digital value to 0 and if the calibrated span it is zero based, the output will go at 4 mA.
– Using the optional LCD keypad ("Configuration of the pressure transmitter using the integral LCD HMI" for further information).
Important
The procedure described in "1" 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 described in point "2" above.
Figure 39: Write-protection pushbutton
2600T Series Pressure transmitters | OI/266/HART-EN Rev. D 33