Campbell Scientific EC150 CO2 and H2O Open-Path Gas Analyzer and EC100 Electronics with Optional CSAT3A 3D Sonic Anemometer - Manual (Page 54)

Appendix A. EC150 Settings
3. The option of a third barometer choice is also available but is rarely
used. A user-supplied barometer option can also be programmed in
the EC100 electronics. This setting determines which pressure sensor
will be used to measure the barometric pressure.
User-supplied Barometer:
When a user supplies a barometer, the setting should be changed to
User Supplied and the appropriate values for gain and offset must be
entered.
Sampling Frequency:
The enhanced barometer is sampled at 1 Hz. If the user supplies an external
pressure sensor, it is sampled at 1 Hz. The on-board pressure sensor is
measured at 10 Hz. In all cases, the pressure sensor measurement is not
synchronized to the CO
2
and H
2
O measurements.
The pressure sensor also allows the setting None for the Pressure Sensor.
This mode is intended for troubleshooting only. The EC100 will use a fixed
value for pressure.
The Pressure Sensor setting is stored in non-volatile memory in the EC150
head.
A.2.10.1 Pressure Gain
This setting is not used unless the Pressure Sensor is set to User Supplied.
Then this setting gives the gain factor (kPa/V) used to convert measured
voltage to pressure. If the Pressure Sensor is set to EC100 Basic or EC100
Enhanced, this setting is not used.
The
Pressure Gain setting is stored in non-volatile memory of the EC100.
A.2.10.2 Pressure Offset
This setting is not used unless the Pressure Sensor is set to User Supplied.
Then this setting gives the offset (kPa) used to convert measured voltage to
pressure. If the Pressure Sensor is set to EC100 Basic or EC100 Enhanced,
this setting is not used.
The Pressure Offset setting is stored in the EC100 electronics.
A.2.10.3 Fixed Pressure Value
If the Pressure Sensor setting is None, the EC150 will use the value of this
setting for the barometric pressure. This mode is intended for troubleshooting
only. In normal operation this setting is not used.
The Fixed Pressure Value setting is stored in the EC100 electronics.
A.2.11 Pressure Differential Enable
This setting should remain disabled. It is used only for closed-path analyzers.
The Pressure Differential Enable setting is stored in non-volatile memory in
the EC150 head.
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