Accubar SDI-12 Barometric Pressure Sensor Operations & Maintenance Manual Rev-B 30 Nov 2017
pg. 19
For example, the following command will set the scale to 70.32 and the offset to 0.0:
aXUU+70.32+0
Similarly, the slope and offset can be set to any values that will produce the desired units.
NOTE: Remember that both a XUU and a XUP command are required for the ACCUBAR
®
to report in
user-defined units.
Setting Station Elevation
The ACCUBAR
®
will usually be installed at an elevation other than sea level. To have the ACCUBAR
®
report the atmospheric pressure at sea level, the sensor's elevation offset from sea level must be
entered. The ACCUBAR
®
has two commands that can be used to enter this elevation offset. The XE
command allows direct setting of an elevation offset which will be added to the measurement to
compute atmospheric pressure at sea level:
aXEou!
where o is adjustment value with units u. u can
have units 0=mB (hPa), 1="Hg, 2=kPa, 3=mmHg,
4=Atm, 5=psia, or 9=user units.
For example, the command:
aXE+20.2+0!
would set the elevation offset pressure to 20.2 with units of mB (hPa).
The other command used to set the elevation offset is the XS command. This command causes the
sensor to make pressure readings and automatically compute a new elevation offset. You can use this
command only if you have a stable, known pressure on the sensor. The command has the format:
aXSdu!
use this form when the sensor is at a stable, known
pressure. The d represents the desired reading and
u the units.
If the sensor was stable at 1005.23 mB, the following command would adjust the elevation offset to
insure the 1005.23 mB reading:
0XS+1005.23+0!
If the sensor was under pressure and stable at 29.921 inches of mercury, the following command would
adjust the elevation to ensure the 29.921" Hg reading:
0XS+29.921+1!
