Measurement Specialties
KPSI
®
Digital Series User’s Manual
Page 17
www.Meas-Spec.com
setting user units
If you want the sensor to read out in units other than feet of water, psi, kPa, centimeters of
water, meters of water, or millimeters of water you will need to use the “XUP” command to set
the units to 9, user units. When user units are selected, the software will use the equation:
Output = psi * slope + offset
Where slope and offset are values you can enter into the system.
The “
XUU
”
command is used to enter the user-defined scale factors. The format is:
aXUUso!
Where “s” is the signed
slope
and “o” is the signed
offset
.
For example, the following command will set the slope to 70.32 and the offset to 0.0 for sensor
“0,” which are the proper values to convert the psi to cm of water:
0XUU+70.32+0!
Similarly, the slope and offset can be set to any values that will produce the desired units.
NOTE: Remember that both an “XUU” and an “XUP” command are required for the
sensor to report in user-defined units.
field calibration
The sensor 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 sensor 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 the signed
field calibration offset value
with
units
“u:” +0=feet,
+1=psi, +2=kPa, +3=cm, +4=m, +5=mm, and +9=user units.
For example, the command:
0XE+0.02+0!
would set the offset pressure of sensor at address “0” to 0.02 feet (u=+0).
The other command used to set the offset is the “
XS
” command, and it has two forms. The first
form causes the sensor to make pressure readings and automatically compute a new offset:
aXS!
use this form of command only if you vent the sensor to the atmosphere.
