Operation
EGM-4 Operator's Manual – Version 4.19
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•
Zero valve failure.
•
Source failure.
However, past history has shown that some customers want to work at lower CO
2
concentrations. As a result, lower alarm settings can be set up by the user if required. If the
low alarm is set to 250 ppm, the low alarm operates when the self-checking facility finds any
of the following system faults:
Error Code
Reported fault
1
Zero to low
2
CO
2
< 250 ppm
3
Analyzer temperature out of range (too cold)
4
Analyzer temperature out of range (too hot)
5
RH > 90%
The above error codes are accompanied by corresponding displays and the error codes are
written to the records. Note, with the porometer and soil respiration/canopy chambers (SRC-
1, CPY-4 and CFX-1), the display warnings still occur but there is no alarm.
The low alarm signal comes out on Pin 7 and is buffered (i.e. able to drive a load).
Setting the High CO
2
Alarm Setpoint
Press key 2 to set the high CO
2
alarm setpoint. The display will show ?????. Enter the
required value.
Note, leading zeros are required for values less than 1000 (i.e. 00900 for
900).
The default EGM-4 high alarm setpoint setting is 2000. As long as the high alarm is set
to the maximum CO
2
ppm range of the instrument, the alarm is inactive. If set to a lower
value, when the CO
2
concentration exceeds the high setting, the alarm will activate.
The high alarm signal comes out on Pin 13 and is not buffered.
7VOUT
Press key 7 (7VOUT) to check/set the analog voltage output. These settings control the
voltage output from the D/A converter in the EGM-4.
Where:
D/A 1V
Selects the maximum voltage output of the EGM-4 (1-5V)
2000
Corresponds to the CO2 concentration (ppm).
The FSD (Full Scale Deflection) analog output value can be set from 1 to 5V. Press key 1
and enter any value between 1 and 5 to set the analog output to the value required. Press
key 2 if you want to change the CO
2
concentration corresponding to the analog output value.
As in the display above, the EGM-4 would be set up with an analog output of 0-1V
corresponding to a measurement range of 0-2,000 ppm.
By default, the analog voltage output is 0-5V. If the displayed values are correct, simply press
the Y key to return to the 2SET menu.
Note. The voltage output must be set to 5V in order for the current output (4-20 mA) to
work properly. If the voltage output is changed to any other value (i.e. 2, 3 or 4V), the
current output facility will not work correctly and should not be used.
D/A 1V = 2000 ppm
Y=OK 1/ 2 NEW VAL
