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10.1 Calibration Summary
The 1732 Oxygen transmitter has a self-calibration and diagnostic system built into the hardware and
software. Once the reference voltages have been set into memory the self-calibration system maintains the
calibration of the transmitter. An automatic update of the zero and span is done every minute.
The 4-20mA outputs can be automatically calibrated with the press of the A
tuned.
One entry for each probe offset is required to optimise the calibration of the oxygen measurement although
an automatic system calibration check can be programmed into the transmitter using certified gasses.
10.1.1 Calibration of the Inputs
The calibration of the analogue inputs is based on the voltage of a temperature compensated voltage
reference integrated circuit. There are 4 voltages generated from the standard reference voltage. They will
vary by about 1% from one transmitter to another but can be trimmed by setting the actual voltages into
Calibration Menu functions #01 to #04.
The calibration should be done 30 minutes or more after the instrument has been on, approximately once
every year. The calibration constants are retained in battery backed memory unless a 'COLD START' is
performed. See Chapter 10.2 Cold Start
Connect a 3 1/2 digit multimeter negative lead to the test point marked 'COM' in the centre of the 1730-1
PCB (labelled 'V-REFS'). Measure the four voltages on the test point marked 1 to 4 with the positive lead of
the multimeter. Enter the measured values in the CALIBRATION menu functions #1 to 4. Whenever new
values are entered, the D/A Section should be re-calibrated. See chapter 10.1.2 Calibration of the Outputs.
10.1.2 Calibration of the Outputs
The easiest way to calibrate the outputs is to select 'Auto Calibrated' in Calibration Menu functions #5 and 8.
If this is selected the outputs will be directed away from the output terminals and back into an analogue input
of the transmitter. The outputs are then tested and a zero and span calibration factor is recorded.
If a more accurate calibration is required select 'Manually Calibrated' in Calibration Menu functions #5 and 8.
This will inhibit the automatic calibration system overwriting the calibration factors. However, the zero and
span factors will need to be manually set. To set the calibration factors use the following steps for each
output:
1. Select Calibration Menu function #05 (function #08 for Output 2), press the O
the option to 'Calibrate 4mA'. Press the E
2. Press the F
UNCTION
2), set this value 4.00mA using the O
3. Measure the actual output current with a digital multimeter.
4. Use the O
PTION
digital multimeter. Press E
5. The output on the digital multimeter should now read 4.00mA. If desired, this value can be fine-
tuned until exactly 4.00mA is read on the digital multimeter. Remember to press the E
after each adjustment to the calibration
6. Press the F
UNCTION
button to set the option to 'Calibrate 20mA'. Press the E
7. Press the F
UNCTION
2), set this value to 20.00mA using the O
8. Measure the actual output current with a digital multimeter.
9. Use the O
PTION
digital multimeter. Press E
10. The output on the digital multimeter should now read 20.00mA. Like before, the value can be fine-
tuned as required.
11. Press the F
UNCTION
button twice to select 'Manually Calibrated'. Press the E
O
PTION
August 2018
1732 Oxygen Transmitter
button to navigate to Calibration Menu function #06 (function #09 for Output
PTION
/ O
buttons to adjust the value on the display to match the reading on the
PTION
to save changes.
NTER
to navigate back to Calibration Menu function #5 and press the O
button to navigate to Calibration Menu function #07 (function #10 for Output
/ O
buttons to adjust the value on the display to match the reading on the
PTION
to save changes.
NTER
button to navigate back to Calibration Menu function #05 and press the
10. I
NSTRUMENT
button.
NTER
/ O
buttons. Press the E
PTION
button.
NTER
/ O
buttons. Press the E
PTION
PTION
C
ALIBRATION
C
button or manually fine-
UTO
AL
button to set
PTION
button.
NTER
NTER
PTION
button
NTER
button.
NTER
Technical Manual
button
55
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