Parameter Descriptions - ABB 261GS Operating Instruction

7.4.5

Parameter descriptions

a
Enabling / disabling (Write Protect)
Via LCD indicator, DTM or handheld terminal.
If "Write Protect" is enabled, it is not possible to configure the
261G/A pressure transmitter. All editing functions on the
indicator are hidden, except for write protection. It is,
however, possible to read out data. Write protection is applied
for the entire device.
IMPORTANT (NOTICE)
In addition, the "Local operation" option can be
disabled via the graphical user interface (DTM) or
a handheld terminal (HHT).
Editing functions are also hidden when the "Local operation"
option is disabled, i.e., the 261G/A pressure transmitter is no
longer configurable via the LCD indicator.
The "Local operation" option can only be enabled via the
graphical user interface (DTM) or a handheld terminal.
Apply Process Variable
Set "Lower Range Value" and "Upper Range Value" with
applied pressure on the device via the process or a pressure
generator.
1. Apply the pressure for the "Lower Range Value" and wait
approx. 30 s until it has stabilized.
2. Setting for "Lower Range Value": Click the right
pushbutton for "OK" – The output current is set to 4 mA.
3. Apply the pressure for the "Upper Range Value" and wait
approx. 30 s until it has stabilized.
4. Setting for "Upper Range Value": Click the right
pushbutton for "OK" – The output current is set to 20 mA.
Set Process Variable
Set "Lower Range Value" and "Upper Range Value" without
applied pressure by entering the corresponding pressure
values via keypad.
28 IM/261Gx/Ax-EN Rev. 08 | 261Gx, 261Ax
Offset
p
3
px
2
1
0 X2
Fig. 19: Offset shift
1 Old zero | 2 New zero | 3 New balance point |
4 Offset shift | 5 New end value | 6 Old end value |
7 Old balance point
This function performs an offset shift of the characteristic so
that it travels through a point specified by the user. This
makes it possible to set the output signal of several measuring
devices that measure the same process variable to the same
value, without the need to perform calibration with applied
pressure.
This function can be performed at any point on the
characteristic under the following circumstances:
— Process variable is within the configured measuring range.
The transmitter has a linear transmission characteristic.
— Enter the desired output current as a percentage to
perform an offset shift for the measuring range.
— When a pressure px is applied, the transmitter displays the
standardized output value x1 as a percentage. Based on
the current application, however, the value x2 should be
displayed. The value x2 in % is set via the LCD indicator.
The transmitter calculates the new zero and the new end
value, and adopts these new settings (see the figure
"Offset shift").
5
4
6
7
X1 100 % I [mA]
A
M10699