OptiCal User’s Manual
16
97079 Issue 9.2, March 2016
OPTIDEW
4
OPTIDEW REFERENCE INSTRUMENT
The OptiCal is supplied with an integrated Optidew chilled mirror reference instrument
to provide a fundamental and traceable reference measurement of the humidity within
the chamber, while being totally independent from the controlling relative humidity
probe. The advantage of this technique is to isolate the control of the chamber from
the control system of the chilled mirror sensor to provide a fast responding and highly
stable system.
4.1
Optidew Display
The Optidew reference has an integral VFD (Vacuum Fluorescent Display) mounted on
the front panel of the OptiCal instrument. To the right of the display is a single multi-
function button which enables the user to select between the Optidew’s two modes of
operation and scroll through the measured and calculated parameters such as ambient
temperature or relative humidity, and indications of system status. The mode can be
either
LOCAL
or
REMOTE
. In
LOCAL
Mode the integral display is active and data such
as temperature and relative humidity are displayed on the VFD screen. In
REMOTE
Mode the display is inactive and the RS232 output is enabled and available via the 9 pin
RS232 communication connector.
Start-up banner
When power is applied to the OptiCal, the Optidew reference display will initially show
test characters for approximately 0.5 seconds, after which the start-up banner will be
displayed for approximately 7 seconds. The instrument will start up in
LOCAL
Mode in
which case the display is active and the RS232 output is not available.
Remote Mode for communication with a PC
On start-up, the Optidew reference is automatically in
LOCAL
Mode. Once the display
has stopped showing the start-up banner it is possible to change between the two modes
by simply holding down the
DISPLAY CONTROL
button for approximately 7 seconds.
In
REMOTE
Mode the display will show
REMOTE MODE
, indicating that communication
with a PC via the RS232 port is possible.
* REMOTE MODE *
rh 49.9 %
t 10.0 °C
LOCAL
Mode
REMOTE
Mode
4.1.1 Selecting Which ‘Screen’ to View on the Display
After the start-up banner has ended, the display will show Screen 1. This displays
the status of the Optidew chilled mirror reference instrument, i.e. DCC and ambient
temperature. To scroll to Screen 2 -
fi
rmly but momentarily press the multifunction
button. It is not possible to view any other screens until the
DATA HOLD
period is
complete. Note that there may be a small delay before the display changes to the next
screen - this is normal. After the
DATA HOLD
period has
fi
nished, Screen 3 will appear.
All eight screens can now be accessed by depressing the multi-function button.
