Pressure Transducer Block (Prtb) - ABB 266 Operating Instruction

Pressure transducer block (PRTB)

Overview
This pressure transducer block is implemented within devices whose primary process sensor has the purpose to measure pressure,
or differential pressure (P-dP). In addition, at the pressure value as primary measurement, there are other variables that can be
selected trough the Channel as input for the Analog Input blocks, these are the Sensor Temperature, the Static Pressure, for
Differential pressure sensors only, and the Scaled PV identified respectively as Secondary, Tertiary and Quaternary variables.
Block diagram
Pressure Transducer Block
Physical I/O
Physical I/O
SENSOR_TYPE
RAW
SENSOR_SERIAL_NUMBER VALUES
STATIC_P_CAL_POINT_HI
INTEGRATION_TIME
STATIC_P_CAL_POINT_LO
SENSOR_RANGE_100%
SENSOR_RANGE_0%
SENSOR_TEMP_CAL_POINT
SENSOR_RANGE_UNIT
Description
The Physical I/O represents the physical interface with the process and is part of the device's Pressure Transducer. The physical I/O
takes care to execute the basic manufacturer device specific algorithm with the purpose to convert the raw signal representing the
measured process value into a digital format. The physical I/O operations are:
– Sampling of the primary raw signal changing according the process changes.
– Validation and Elaboration of the sampled primary raw signal
– Linearization and Compensation
Result of the above operations is the RAW_VALUES produced in output of the physical I/O, see the Block Diagram, and used as
input for the Pressure Transducer Block.
The first Pressure Transducer Block operation is the Calibration/trimming of the RAW_VALUES in order to adjust its digital value to
match the real pressure measured by the Sensor block.
The RAW_VALUES after the calibration became the calibrated Measured Values (MV) represented by the PRTB_CAL_VALUE and,
for differential sensors only, PRTB_STATIC_P_TRIM_VALUE.
These Measured Values matches and represents the real inputs sampled by the sensor and any further calculation has the scope to
transform them to a Process Variables (PV).
In this perspective the first calculation applied is the elevation/suppression within the PV-Bias/Offset step executed for different rea-
sons like the correction of the mounting position or for example in any condition where part of the measure must not be considered
as part of the process.
PV_Bias/ Offset
[PV = MV +/- BIAS_VALUE]
DESIRED_PRIMARY_VALUE
CAL_VALUE
RESET_BIAS
(1) (MV) BIAS_VALUE
Calibration
/ Trimming
DESIRED_STATIC_P_VALUE
RESET_STATIC_P_BIAS
CAL_POINT_HI
STATIC_P_BIAS_VALUE
CAL_POINT_LO
CAL_MIN_SPAN
STATIC_P_MIN_SPAN
STATIC_P_
TRIM_VALUE (MV)
(2)
PV
PdP Ranging Transfer Function
SV (3)
PRIMARY_VALUE_RANGE_100% QUATERNARY_LIN_TYPE
PRIMARY_VALUE_RANGE_0% QUATERNARY_CUT_OFF
PRIMARY_VALUE_RANGE_UNIT QUATERNARY_LIN_POINT
Static Pressure Ranging
TERTIARY_VALUE_RANGE_100%
TERTIARY_VALUE_RANGE_0%
TERTIARY_VALUE_RANGE_UNIT
Sensor temp Ranging
SECONDARY_VALUE_RANGE_100%
SECONDARY_VALUE_RANGE_0%
SECONDARY_VALUE_RANGE_UNIT
2600T Series Pressure transmitters | OI/266/FF/ADD-EN Rev. B 9
PRIMARY_VALUE
(PRESSURE P-dP)
AI _CHANNEL = 1
PdP Output Scale
QUATERNARY_VALUE
(SCALED_PV [%])
QUATERNARY_RANGE
AI _CHANNEL = 4
0 – 100 %
TERTIARY_VALUE
AI _CHANNEL = 3
(STATIC PRESSURE)
SECONDARY_VALUE
AI _CHANNEL = 2
(SENSOR TEMPERATURE)