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9� By means of calibrated pressure generator, apply the same pressure already set in URV during step 6.
Output should equal 20mA. In case output isn't 20 mA, please go to step 10.
10. In order to calibrate full scale output, please apply firstly pressure equal to full scale pressure.
Then you can proceed to set Upper Trim value with Device Variable Trim method (fast key 1, 2, 6, 3, 3;
anyhow please consider Lower Trim value has to be done).
Now output should be the same of the full scale pressure.
11� When transmitter Output Damping is needed, please set PV Damping (fast key 1, 3, 6) to the proper value.
12� Press the left arrow key until the HART Communicator is off-line. Then switch off the power.
At this point the pressure transmitter can be installed in the process.
Autozero using HART communication
With the transmitter installed and connected to the measurement instrument without any pressure applied
and with the system at the working temperature, once temperature itself is stable, i.e. with a possible variation
of ± 1°C, Autozero can be performed. If the zero trim function is selected (fast key 1, 2, 6, 3, 1) the output will
be modified to show zero pressure. Such a task is carried out by the transmitter electronics automatically by
regulating digital PV to zero while analog output will be 4 mA.
Usually an Autozero is all that is needed once installation is completed as the transmitter span has been
calibrated at the factory.
In case the Full Scale Output is not correct when tested with a calibrated pressure source or dead weight
tester, the transmitter span can be regulated using the Device Variable Trim method (fast key 1, 2, 6, 3, 3).
Please apply Zero Pressure firstly and follow the prompts on the handheld HART Communicator. Once
completed, please apply a known calibrated full scale pressure to the transmitter and follow the prompts on the
handheld HART Communicator. Once completed, the digital PV will be corrected to full scale output.
Transmitter functions using HART communication
(with fast key sequences)
Autozero (1, 2, 6, 3, 1)
Digital modification to zero: it affects both the digital and analog output. Please consider this operation is diffe-
rent from Lower Sensor Trim as Autozero has to be done ONLY at zero pressure.
Reset Autozero (1, 2, 6, 3, 2)
Reset Autozero correction.
Device Variable Trim (1, 2, 6, 3, 3)
Digital modification to zero and full scale: it affects both the digital and analog output.
Please consider this operation is different from Autozero as Lower Sensor Trim can be made at positive pres-
sures, i.e. above zero.
Note: Such an operation has to be carried out with a known calibrated pressure source only.
D/A trim (1, 2, 6, 2)
This function is used to match the digital representation of the analog output with its real analog loop current.
Note: Such an operation should be carried out with a known calibrated current (mA) meter only.
Re-range
The 4mA and 20mA points, i.e. LRV and URV respectively, can be regulated in order to improve output reso-
lution. This means a Re-range (also called "Turndown") ratio of 3:1 is possible.
Please consider accuracy data is reliant upon the Full Sensor Range without applying any turndown.
Note: In case pressure applied to the transmitter is not in the range of the 3:1 turndown ratio, the transmitter
will refuse the command.
Such a condition will be shown by the output not adjusting to 20mA after a few requests.
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80636B_MAN_HMF - HWF_05-2022_ENG
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