Michell Instruments XZR200, User Manual

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XZR200 User’s Manual
Michell Instruments 13
CALIBRATION
4 CALIBRATION
The XZR200 will require routine calibration determined by the application, installation
and user preferences. The analyzer can be con fi gured for manual or automatic
calibration by changing the jumper on the board. Calibration is achieved by connecting
the calibration input to GND and monitoring the status of the digital cycle output or by
visually monitoring the on-board green LED. During the calibration process the output
will either automatically calibrate to a fi xed reference or can be manually calibrated to
any output by way of a PCB mounted potentiometer.
The fi xed reference is factory set to 20.7% O
2
for calibration in normal air though this
value may be altered via the RS232 interface for calibration with a reference gas of any
known oxygen concentration.
4.1 Automatic Calibration
Ensure the XZR200 is con fi gured for automatic calibration. See Section 2.1 on
Con fi guration.
1. Place the sensor probe in the calibration gas, typically normal air.
2. Allow the output to stabilize for at least 5 minutes. Allow 10 minutes if
powering from cold.
3. Apply GND to the CALIBRATE input (PIN 6) for a minimum of 12 seconds.
During the 12 seconds, the CYCLE output (PIN 7) and the green LED will
go high/on, blink rapidly, go high/on, go low/off then return to cycling
normally to indicate normal operation has resumed. At this point remove
GND from PIN 6.
4. The output will now track to the correct value for the calibration gas.
Calibration is complete. Calibration values are retained on power loss.
4.2 Manual Calibration
Ensure the XZR200 is con fi gured for manual calibration. See Section 2.1 on Con fi guration.
1. Place the sensor probe in the calibration gas, typically normal air.
2. Allow the output to stabilize for at least 5 minutes. Allow 10 minutes if
powering from cold.
3. Apply GND to the CALIBRATE input (PIN 6) for a minimum of 5 seconds
or until the CYCLE output and green LED blink at a steady 1Hz. Remove
GND from PIN 6. Manual calibration is now initialized.
4. Adjust the MANUAL CAL POT until the output equals the correct value of
the calibration gas concentration.
5. Re-apply GND to PIN 6 for a minimum of 5 seconds. During the 5 seconds
the CYCLE output/LED will blink rapidly, go high/on, go low/off then
return to cycling normally to indicate normal operation has resumed. At
this point remove GND from PIN 6.
6. The output will now track to the correct value for the calibration gas.
Calibration is complete. Calibration values are retained on power loss.