page 9
back to atmospheric settings. A long press of the pressure correct button changes the
unit back to the Viewing Dewpoint Mode. Pressing the ‘Mode’ button changes the unit to
the View/Set Gas Pressure sub-state. The display has the ‘SET’ and ‘PSI’ legends on
and alternately shows
*$6
and the currently set value for the gas pressure. The up, down
and pressure correct buttons operate in the same manner as in the Sensor Pressure
sub-state. Pressing the ‘Mode’ button changes the unit back to View/Set Sensor Pres-
sure sub-state, and so forth.
The factory default settings are: 14.7psi for both sensor and gas pressure and pressure
correction disabled.
When Pressure correction is disabled all dewpoints are computed by assuming that both
Sensor and Gas Pressures are 14.7psi.
5.2.2 Viewing Temperature at Sensor
In this mode the user can view the temperature at the sensor inside the sampling cham-
ber, signified by the flashing ‘TEMP’ legend on the lower left of the display. The available
units in which to view the temperature are °C and °F. The up and down buttons switch
back and forth between these units.
Pressing the ‘Mode’ button changes to the Start Autocal Mode.
5.2.3 Start Autocal Mode
In this mode the user is prompted to confirm that Autocal should be initiated. This mode
can be skipped by pressing the ‘Mode’ button to go to the View Serial Number Mode or
by cancelling with the down or pressure correct buttons which displays the word
&$1
for
1/2 second and goes back to the Viewing Dewpoint Mode.
Autocal can be initiated by pressing the ‘up’ button. The unit will check if the sensor is in
the sampling chamber, if not it will prompt the user to pull the sensor out of the desiccant
by beeping and displaying alternately
38/
and
287
. Pull the sensor actuator out, when
this message appears.
Since Autocal is a irreversible recalibration of the instrument there is one more beeping
and visual prompting with alternating
&1)
and
$&"
. The down and pressure correct but-
tons allow cancelling the Autocal, while the up button confirms it. The unit starts taking
measurements for 1 minute while displaying alternately flashing
$&
. During this time the
user should occasionally pump saturated air using the calibration bulb into the sample
chamber (see Autocal Instructions). An alternating
6(1
and
/2
after one minute,
accompanied by a beeping, indicates the sensor has a reading too low to be from a satu-
rated sensor. This error will cause Autocal to be cancelled. However, if the sensor read-
ing is within range of a saturated sensor, a new calibration is calculated (some numbers
flash on the display),
(1'
is displayed for 1 second, and the new calibration values are
saved in EEPROM.
5.2.4 Viewing Serial Number Mode
In this mode the user can view the serial number of the sensor. The display shows the
serial number by alternately displaying
;61
and the number. If the number is larger than
1999 then it is displayed in 2 segments, first segment is the thousands signified by the
x10
3
legend in the upper right corner of the display and the second segment is the units.
