© 2010 SST Sensing Ltd 8 www.sstsensing.com
DS0074 Rev 7
RS232 USER CONFIGURABLE OPTIONS
Changing the Automatic Calibration Value
The system is factory set to automatically calibrate to
20.7% O
2
to allow simple calibration in normal air. The
auto calibration value is factory set to 20.7% to take into
account average humidity in the atmosphere. If a
calibration with a gas of a different known O
2
concentration is required the factory set value may be
changed via the RS232 interface.
Connect the O2I-FLEX via the RS232 interface to
the PC.
Press Enter then enter your security password.
Press Enter to access the menu screen.
In the Configuration menu (menu 2) enter the auto
calibration value screen (option 1 - Enter
Auto Calib).
The number entered should be the oxygen
concentration (%) of the calibration gas to 2 decimal
places. Press Enter to save.
The new Automatic Calibration value is now stored
in memory. This value is retained on power loss.
If calibration is required with a different gas of known O
2
concentration and access to the RS232 menus with a PC
is not available in order to change the calibration
percentage, a manual calibration must be performed.
Variable Output Filtering (Td Averaging)
The O2I-FLEX is factory default to use adaptive output
filtering to give an optimum balance between output
stability and response to oxygen changes. However this
balance may be altered by the customer to suit the needs
of the application.
Connect the O2I-FLEX via the RS232 interface to
the PC.
Press Enter then enter your security password.
Press Enter to access the menu screen.
In the Configuration menu (menu 2) enter the Td
average screen (option 2 - Enter Td Averaging).
The number entered should be between 0 and 200.
0 for adaptive filtering (recommended), 1 for very
fast and dynamic output response but relatively
unstable to 200 for an extremely stable output but
very slow response to oxygen changes.
Press Enter to save.
The new averaging value is now stored in memory.
This value is retained on power loss.
Adjusting the Minimum and Maximum Ranges of the
Analogue Outputs (4-20mA and 0-10V
DC
)
The O2I-FLEX is factory default to output a range of
0-25% O
2
via its two analogue outputs. This range can be
expanded to 0-100% O
2
as described on Page 6. When
the unit is reconfigured to output 0-100% O
2
the user also
has the option to fully customise the output ranges via
RS232. This is extremely useful in applications where the
O
2
variation is within a narrow band as it allows the
analogue outputs to be tailored to this limited range.
Ensure the O2I-Flex is configured for 0-100%
operation, see Page 6.
Connect the O2I-FLEX via the RS232 interface to
the PC.
Press Enter then enter your security password.
Press Enter to access the menu screen.
In the Configuration menu (menu 2) enter the
maximum range screen (option 3 - Enter O2 Max
Range).
The number entered should be between 1.00 and
100.00 to represent the maximum output range. The
number must also be greater than the saved
minimum range.
Press Enter to save the ESC to return to the
configuration menu.
Enter the minimum range screen (option 4 - Enter
O2 Min Range).
The number entered should be between 0.00 and
99.00 to represent the minimum output range. The
number must also be less than the saved maximum
range.
Press enter to save.
The new ranges are now stored in memory and are
retained on power loss.
An example of changing the min and max output ranges
would be in an normal air atmosphere where the O
2
range
is between 20-21%. The user could set the minimum
output range to 19% and the maximum output range to
22% and the outputs would vary linearly in between. The
min and max ranges lock out the outputs at the set limits
so 19% O
2
or lower would set the analogue outputs to
0V
DC
/4mA and 22% O
2
or higher would set the analogue
outputs to 10V
DC
/20mA.
The min and max range adjustment does not apply to the
RS232 output and is overruled if the unit is reconfigured
for 0-25% operation.
O2I
-
Flex
Oxygen Interface
