Local Push Buttons; Installing/Removing The External Pushbuttons; Operations; Wet Ranging Operation (Sw 3 = 1) - ABB 2600T Series Operating Instructions Manual

9 Local push buttons

Three push buttons (Zero, Span and Write Protection) are
located under the identification nameplate.
To gain access to the local adjustments release the fixing
screws of the nameplate and rotate clockwise the identification
plate.
Warning. Operating the control buttons with a magnetic
screwdriver is not permitted.

9.1 Installing/Removing the external pushbuttons

1. Loosen the screws that fix the nameplate plate and slide
the plate to gain access to the local adjustments.
2. Loosen the pushbuttons assembly screws (1) holding
down the plastic element which is spring loaded.
3. Remove the gasket (3) which is positioned below the
pushbutton plastic cover (2)
4. The three pushbuttons (4) and the relevant springs (5)
can now be removed from their seat.
Figure 38: External pushbutton assembly components

9.2 Operations

The Zero and Span buttons are enabled by default but can be
disabled with the PB_LOCAL_OP_ENA parameter.
Write protection pushbutton (4) prevents the configuration data
from being overwritten by unauthorized users.
If write protection is enabled, the Zero and Span 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):
1. First, use a suitable screwdriver to press the switch down
fully.
2. Then turn the switch clockwise by 90°.
1
4
2
3
Figure 39: Pushbutton functionalities
1 – Identification nameplate
2 – Zero pushbutton
3 – Span pushbutton
4 – Write-protection pushbutton
Important. To deactivate the switch, push it down slightly and
then turn counter clockwise by 90°.
Important. The function of the Z and S buttons changes
accordingly with the SW 3 selection.

9.2.1 Wet ranging operation (SW 3 = 1)

The Z button (2) performs the 'Lower Range Setting' operation
and sets as 0% the actual measured pressure value. After the
'Z' button is kept pushed for more than 2 seconds, when
released, the pressure value measured in input is written in the
PRTB_SCALE_IN_0%. The PRTB_SCALE_IN_100% is
shifted in order to keep the same SPAN
Before:
— SPAN = (PRTB_SCALE_IN_100% - PRTB_SCALE_IN_0%)
After:
— PRTB_SCALE_IN_0% = PRTB_TRIMMED_VALUE
— PRTB_SCALE_IN_100% = SPAN + PRTB_SCALE_IN_0%
The Span button performs the 'Upper Range Setting' operation
and sets as 100% of the calibration scale the actual measured
pressure value. After the Span button is kept pushed for more
than 2 seconds, when released, the pressure value measured
in input is written in the PRTB_SCALE_IN_100%. The SPAN
changes as consequence.
— PRTB_SCALE_IN_100% = PRTB_TRIMMED_VALUE

9.2.2 PV Scaling operation (SW 3 = 0)

The Zero button performs the 'zero elevation/suppression'
operation. After the Zero button is kept pushed for more than 2
second, when released, the PTRB_SECONDARY_VALUE_1 is
zeroed. The zeroing is achieved by an internal writing of 0.0 in
the PTRB_DESIRED_VALUE. The difference between PTRB_
DESIRED_VALUE and the PTRB_TRIMMED_VALUE is written
in the PTRB_BIAS_VALUE.
— PTRB_BIAS_VALUE =
(PRTB_TRIMMED_VALUE - PRTB_DESIRED_VALUE)
The PTRB_BIAS_VALUE (positive or negative) is added in the
calculation algorithm at the PTRB_TRIMMED_VALUE for the
production of the PTRB_SECONDARY_VALUE_1.
— PTRB_SECONDARY_VALUE_1 =
(PRTB_TRIMMED_VALUE + PRTB_BIAS_VALUE)
The Span button performs the 'Reset zero elevation/
suppression' operation. After the Span button is kept pushed
for more than 1 second, when released, the
PTRB_BIAS_VALUE is reset to Zero eliminating in this way any
effect of elevation or suppression for the
PTRB_SECONDARY_VALUE_1 that, after this operation,
returns to produce again the same value of the
PTRB_TRIMMED_VALUE.
—
PTRB_BIAS_VALUE = 0.0
— PTRB_SECONDARY_VALUE_1 =
PTRB_TRIMMED_VALUE
2600T Series Pressure transmitters | OI/266/PB-EN Rev. E 33
9 Local push buttons