Field Calibration
The ACCUBUBBLE may have a change in the calibration over time. The most common change is
a change in sensor zero (value read when the pressure is 0). The ACCUBUBBLE has two
commands that can be used to adjust for this change in zero. The XE command allows direct
setting of an offset which will be added to the measurement to compensate for this drift:
aXEou!
where o is adjustment value with units u. u can have
units 0=feet, 1=psi, 2=kPa, 3=cm, 4=m, 5=mm, and
9=user units.
For example, the command:
aXE+0.02+0
would set the offset pressure to 0.02 with units of feet.
The other command used to set the offset is the XS command. This command causes the sensor to
make pressure readings and automatically compute a new offset. You can use this command only if
you vent the sensor to the atmosphere or have a stable, known pressure on the sensor. The
command has the format:
aXS!
Or
aXSdu!
use this form only when the sensor is vented to the
atmosphere
use this form when the sensor is at a stable, known
pressure. The d represents the desired reading and u the
units.
For example, after venting the sensor to the atmosphere, the following command would cause a new
offset to be computed:
0XS!
If the sensor was under pressure and stable at 4.65 feet, the following command would adjust the
offset to ensure the 4.65-foot reading:
0XS+4.65+0!
If the sensor was under pressure and stable at 4.65 psi, the following command would adjust the
offset to ensure the 4.65-psi reading:
0XS+4.65+1!
When the ACCUBUBBLE is done with the self-calibration, the new offset is stored into memory.
A subsequent aD0! command will display this offset in the current units of pressure. The offset can
also be displayed using the M3 command.
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Summary of Contents for Accububble 56-0131-50-1
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