Honeywell Manning AirScan iR Instruction And Installation Manual page 19

STEP 1
4-20 mA Output Calibration
This procedure calibrates the 4/20 mA output to
match a PLC input converter or various devices that
interpret the 4/20 mA signal output to ensure the
4 mA output rests at a true 4 mA even with minor
mismatches in load resistance, long feed wiring, or
adverse environmental conditions.
Start: Set meter to mV DC and place meter leads on
Test(+) and Test(—) respectively (see Figure 9).
• Press and hold the "zero" button (S1) for 5 seconds
or until the "calibrate" LED is blinking slowly and the
"system" LED is continuous ON. Make sure the "mA
Fault" LED is OFF.
• Adjust the zero potentiometer until the output reads
3.99 to 4.01 mA (39.9 to 40.1 mV). This sets the 4 mA
resting point. Make small adjustments and wait for
the output to change because adjustment response
is delayed between source pulses.
Figure 23. 4 mA output programming calibration mode
Exit: Press and hold the "zero" button (S1) for one
second or more until the "calibrate" LED turns off.
The "system" LED will resume the previous state,
either "filtered" or "non-filtered" output mode. This
indicates the parameters are now programmed into
memory.
AirScan iR - Industrial
STEP 2
Zero Calibration
This procedure sets the internal reference that
is indicative of 0 ppm of target gas. It MUST be
performed before proceeding or every other
setting will be offset and inaccurate. The "zero"
can be initiated at any time as long as a neutral gas is
flowing through the calibration port or the surrounding
air is known to be FREE of any target gas down to 1
ppm.
Start: Apply pure nitrogen (N2) into the calibration
port at a rate of .6 liter/min. for at least 3 minutes
(OR until output signal is within ± .02 mA of signal
deviation/change).
• Press and hold the "zero" button (S1) for
approximately 1 second or until the yellow
"calibrate" LED is continuous ON.
• When yellow calibration LED is continuous ON,
release the "zero" button. The "calibrate" LED will
turn off and the unit will be zeroed. See example
below.
Figure 24. Zero programming calibration mode
Exit: System will automatically resume previous
mode, either "normal" or "no dead band" mode. This
indicates the parameters are now programmed into
memory.
Place multi-meter leads on Test(+) and Test(—) and
ensure the output is steadily resting between 3.9 to
4.1 mA (see Figure 9 on next page). If this isn't the
case, initiate the auto "zero" procedure once again.
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