Revision 14
131 August 02, 2019
5.19.2 Calibrating Analog Outputs
This operation requires that the user open up the analyzer. If the system
conforms to the Class 1, Division 1 classification, ensure that these
requirements are met at the conclusion of the calibration procedure when
the system is closed up.
Each analog output must be calibrated individually. To calibrate analog outputs, a multimeter
set to measure milliamps must be connected across the analog output, and the analog output
must be powered, as the analyzer motherboard does not provide power to the analog
outputs. When the analog output is correctly powered, a green LED will glow on the
electronics board next to the AO terminal block.
To calibrate analog output 1:
a) Connect the multimeter to the AO 1 terminal block on the right side of the motherboard.
b) Press the Calibrate AO 1 button in the application program. In the Analog Output 1
Calibration box, there are six user-adjustable fields, arranged. The Scaled Value for zero,
span, and fail-safe tell the analyzer what currents should be output to the AO when the
data point being sent to the AO has a value equal to its minimum or maximum output
value or when the analyzer is in bypass (fail-safe) mode.
c) Press the Output Zero button. The analog output will attempt to output 4 mA. Note the
actual mA output on a meter and enter this value into the Meter Reading field below the
Output Zero button. Then press the Auto Cal button located below the Meter Reading
field. This will cause the analog output to be calibrated to exactly 4 mA.
d) Once the multimeter reads the exact value, press the Output Span button and repeat the
process. This time, the meter should be made to read exactly the value in the scaled
value field in the span column, usually exactly 20 milliamps.
e) Calibrate the fail-safe position. The fail-safe position is the value that the analog output
will output when the analyzer is in bypass mode, and is a value outside the standard
scaled range of the analog output. For example, if the analog output is scaled to output 4
to 20 milliamps, the fail-safe value could be 3 or 21 milliamps. To calibrate the fail-safe
position, press the Fail-Safe button and follow the same procedures as the Zero and
span calibration.
f) Once the analog output is correctly calibrated, press the Capture button to write this new
configuration to the analyzer.
g) Test that the output works correctly using the Analog Output Test box. Enter a value
between 0 and 100 into the Test (Percent) field and ensure that the reading on the
multimeter is the same as the reading in the Test mA field. If it is not, the calibration is not
correct, and needs to be changed. If it is, the calibration is correct. Press the Calibrate
AO 1 button again to close this field
The above process should be repeated for each analog output. Once all analog outputs are
calibrated, press the Permanent Configuration Write to Analyzer ( ) button to permanently
write the new Analog Output configuration to the analyzer.
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