Sensor Temperature Trimming; Parallel Shift (P-Dp); Parallel Shift (Static Pressure); Transfer Function - ABB 2600T Series Operating Instructions Manual

12.1.5 Sensor temperature trimming

With this operation the PRTB_TEMPERATURE is automatically
adjusted, in order to match the real value of the sensor
temperature. The following sequence of operations is required:
1. Select the engineering unit of the temperature in the
PRTB_TEMPERATURE_UNIT (Temperature Unit Only)
2. Read the Sensor Temperature value from the
PRTB_TEMPERATURE.
3. If this value doesn't match the known Sensor
Temperature of the transducer, enter the correct value in
the PRTB_SENSOR_TEMP_TRIM_VALUE and write to
the transmitter. This writing executes an internal algorithm
that produces the new correction coefficients.
4. Read again the PRTB_TEMPERATURE and check if its
value matches the real Sensor temperature value.

12.2 Parallel shift (P-dP)

In case the process (dp or p) cannot be led to 0 it is possible
correct the measure performing the Parallel Shift operation.
Typically this operation is applicable for Level measurements.
Having the possibility to see/read the actual measure in
percent, if it is not what expected, enter the percent of what
the process should measure. The correction consists in the
shift of the calibration range values in order to produce in
output the measure with the desired percentage. The parallel
shift can be done in two ways:
— Locally using the optional LCD keypad from the menu
"Device Setup/Process Variable/Parallel Shift".
— From remote station via profibus communication writing
the desired percent value in the
PTRB_PARALLEL_SHIFT_PV
In this way the Calibration Range Values PRTB_SCALE_IN 0%
and PRTB_SCALE_IN 100% are changed due to their shifting.
Important. After the parallel shift execution, the percent value of
the AI1_OUT matches the desired percentage only if the
PRTB_LIN_TYPE is set to Linear.
This makes it possible to set the output signal of several
measuring devices that measure the same process variable to
the same value without having to perform a calibration with
applied pressure.
E.G. the transmitter output can be adjusted to gauge-glass for
level measurement.
This function can - under the following circumstances - be
carried out at any point on the characteristic:
— Process variable within the adjusted measuring range -
transmitter with linear transfer function.
— Write protection on the transmitter must not be
activated.
Figure 45: Parallel shift
When a pressure px is applied, the transmitter displays the
standardized output value x1 in percent.
Due to the present application the value x2 should be
displayed.
Enter this new value x2 in the line PRTB_PARALLEL_SHIFT_PV,
the transmitter calculates the new zero and the new final value
and adopts these new settings in the PRTB_SCALE_IN 0% and
PRTB_SCALE_IN 100%

12.3 Parallel shift (Static Pressure)

This operation is same as for the P-dP above described but
available for dP sensors only. It is executed by writing the
desired output in percentage value in the
PRTB_PARALLEL_SHIFT_SP. This function performs an offset
shift of the measuring range so that the PRTB_STATIC_P_
SCALE_IN 0% and PRTB_STATIC_P_SCALE_IN 100% are
shifted in order to produce in output the desired value.

12.4 Transfer function

The 266 Pressure Transmitter provides a selection of output
functions, as follows:
— Linear for differential, gauge and absolute pressure or
level measurements
— Sq. Root (x) for flow measurements using restriction type
primary element, like orifice plate, integral orifice, Venturi
or Dall tube and similar.
— Sq. Root (x3) for open channel flow measurements using
rectangular or trapezoidal weir
— Sq. Root (x5) for open channel flow measurements using
V-notch (triangular) weir.
— Bidirectional Flow
— Custom linearization table
— Cylindrical lying tank
— Spherical tank
These output functions can be selected writing in
PRTB_LIN_TYPE activated using a Configuration Tool (Digital
LCD Integral Display,or PC based software as Asset Vision
Basic). The transfer function can be applied to the Process
Variable only or also to the indication (in engineering units).
2600T Series Pressure transmitters | OI/266/PB-EN Rev. E 43
12 Operations