6
An Air Temperature Probe and a Type D2 Chilled Mirror Sensor are located in the
Test Chamber. The relative humidity and temperature of the chamber are
programmable from the Scrolling Menu.
The 40 x 8 character backlit LCD displays Dew Point (C or F), Chamber
Temperature (C or F), and Percent Relative Humidity simultaneously.
The Automatic Balance Cycle (ABC) can be set to balance the sensor optics at
preset times and intervals or can be initiated manually at any time.
An analog output is available on the Panel as either 0 to 5VDC or 4 to 20 ma, and it
can be set to follow any parameter with individually programmable high and low
points. The output can be set to
Track
the selected parameter value during the ABC
cycle or
Hold
the last value prior to the ABC cycle.
The half duplex configured RS-232C serial port can be used to remotely control the
calibrator operation, and to output data to a data recording device.
3.3 OPERATING CONTROLS
The RH CALIBRATOR operates entirely under microprocessor control. State-of-the-
art software provides the opportunity to include a flexible, informational, and user
friendly interface. The setup and operation of the control unit can be programmed via
the front panel keypad or the RS-232 serial port.
LCD Graphics Display:
Displays three parameters simultaneously, time, date,
operational status, sensor mirror condition, and alerts the user to fault conditions.
When activated from the Scrolling Menu, the AT SETPOINT (chamber
temperature) and the RH SETPOINT (relative humidity), are displayed. The
display of Dew Point may also be selected with the Keyboard.
Keypad:
A membrane type keypad allows the user to enter setup and instrument
control information. A Scrolling Menu guides the user through the setup
procedure. The Setup Parameters include RH SETPOINT, AT SETPOINT, time,
date, analog output parameter and scale, ABC start and interval, and serial port
settings.
SERVOLOCK ™:
The SERVOLOCK feature continuously displays the servo
control loop status. This is especially useful when the sample dew point is
varying widely or quickly. When SERVOLOCK is displayed, the system is locked
on to and tracking the dew point.
ABC Cycle:
The Automatic Balance Cycle checks for proper operation of the
system and re-balances the sensor to compensate for changes in reflectivity of
the mirror due to aging, optics drift, or minor contamination due to impurities in
the sample gas. The on board real time clock permits the user to program the
