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5.4 Current Loop Calibration
A current loop option can be ordered that will provide a 0-20mA or 4-20mA output on
the analog output. This calibration must be repeated every time an A/D - D/A calibration
is performed. To calibrate the current output, perform the following steps:
1. Perform an A/D - D/A calibration as outlined in Section 5.3.
2. Connect a Multimeter capable of measuring milliamperes to the analog output
on the rear panel. Note: When measuring the current output with a
multimeter or similar low-impedance current measuring device, a 400-
450 ohm resistor must be placed in series with the meter to simulate a
load. Failure to do this will result in erroneous readings.
3. From the front panel, press SETUP-DIAG. Press NEXT until D/A
CALIBRATION appears and press ENTR. Press CFG and the properties for
analog output Channel 0 will be displayed on the top line. The display should
show something like:
NEXT EXIT
DIAG D/A 0) O3_CONC_1,CURR, NOT CAL
CAL SET
4. This indicates that channel 0 is setup for current output and has not been
calibrated. If the display shows VOLT instead of CURR then the channel
must be setup for current output. To do this, press SET, select CURR as the
output type and press ENTR.
5. Next press CAL to begin the calibration. At this point the display should
show:
UP10 EXIT
DIAG D/A CAL O3_CONC_1,CURR, ZERO
UP DOWNU100 DN10 D100 ENTR
6. The zero point for current output can now be set. Pressing UP, UP10 and
U100 will step the zero point up in increments of 1, 10 and 100 steps. The
P/N 02826B1 Teledyne API Model 450H O
3
Monitor Instruction Manual - Page 43