ABB 266 Operating Instruction page 16

266 Models - FOUNDATION Fieldbus
Sensor calibration
The transmitter makes available to the user some operations that can be useful during the device life cycle. These operations are
supported and can be executed with the EDD based configuration tools, or also by following the instructions/descriptions below.
Sensor trimming/calibration
The scope of the sensor trimming/calibration is to adjust and make accurate as much as possible the sensor conversion to a
pressure value in digital format.
The sensors of the 266 are calibrated/trimmed in the factory to the customer's specified measuring range therefore it could be
necessary change or correct the sensor calibration later on as maintenance operation.
Two points are necessary to perform a sensor calibration. Low sensor calibration point (Zero) writing in PRTB_CAL_POINT_LO
and High sensor calibration point (Span) writing in PRTB_CAL_POINT_HI. The minimum distance from the two points must be
greater than minimum span PRTB_CAL_MIN_SPAN.
P-dP sensor low trimming
With this operation the PRTB_CAL_VALUE is automatically adjusted, in order to match the real value of the pressure applied in
input, in the low part of the working range. The following sequence of operations is required:
– Apply a reference pressure in input using a reference pressure generator.
– Select the engineering unit of the measure in the PRTB_CAL_UNIT (Pressure Unit Only)
– Read the measure produced by the transmitter from the PRTB_CAL_VALUE.
– If this value doesn't match the pressure applied in input, enter the correct known applied pressure value in the
PRTB_CAL_POINT_LO and write to the transmitter. This writing executes an internal algorithm that produces the new correction
coefficients.
– Read again the PRTB_CAL_VALUE and check if its value now matches the applied pressure.
P-dP sensor high trimming
With this operation the PRTB_CAL_VALUE is automatically adjusted, in order to match the real value of the pressure applied in
input, in the high part of the working range. The following sequence of operations is required:
– Apply a reference pressure in input using a reference pressure generator.
– Select the engineering unit of the measure in the PRTB_CAL_UNIT (Pressure Unit Only)
– Read the measure produced by the transmitter from the PRTB_CAL_VALUE.
– If this value doesn't match the pressure applied in input, enter the correct known applied pressure value in the
PRTB_CAL_POINT_HI and write to the transmitter. This writing executes an internal algorithm that produces the new correction
coefficients.
– Read again the PRTB_CAL_VALUE and check if its value now matches the applied pressure.
Static pressure low trimming
With this operation the PRTB_STATIC_P_TRIMMED_VALUE is automatically adjusted, in order to match the real value of Static
Pressure applied at the transducer in the lower part of the range. The following sequence of operations is required:
– Select the engineering unit of the measure in the PRTB_STATIC_P_CAL_UNIT (Pressure Unit Only)
– Read the Static Pressure value from the PRTB_STATIC_P_TRIMMED_VALUE.
16 OI/266/FF/ADD-EN Rev. B | 2600T Series Pressure transmitters