Campbell Scientific CPEC200 Closed-Path Eddy-Covariance System - Manual (Page 57)

Appendix A. CPEC200 Diagnostics
If the program is configured to use the valve module (constant
VALVE_MODULE = True), but the valves are not being used
( valve_number = 0), there are several possible values for valve_status that
relate to the temperature of the valve module. valve_status also depends on
the temperature of the optional scrub module if it is installed. See notes on bits
2 and 1 for more information on valve module and scrub module temperature
control.
• Valves are in standby mode (temperature control is disabled) is
displayed if valve module temperature control is disabled
( valveTctl_ON = False). This is the normal state for the valve
module when it is not in use.
The rest of the possible values for valve_status given below, apply only when
valve module temperature control is enabled.
• Valves are ready is displayed if the valve module temperature is
within its operating range and the scrub module (if installed)
temperature is also within its operating range.
• Valves are too cold is displayed if the valves are below the minimum
operating temperature. See notes on bit 2.
• Valves are too warm is displayed if the valves are above the
maximum operating temperature. See notes on bit 2.
• Valve temperature problem is displayed if the valve temperature is not
defined (NAN). See notes on bit 2.
• Scrub module is too cold is displayed if the valve module is within its
operating range, but the scrub module is too cold. See notes on bit 1.
• Scrub module is too warm is displayed if the valve module is within
its operating range, but the scrub module is too warm. See notes on
bit 1.
• Scrub module temperature problem is displayed if the scrub module
temperature is not defined (NAN). See notes on bit 1.
If a valve has been selected ( valve_number > 0), there are several possible
values for valve_status.
• Valve flow is OK is displayed if the valve flow is within an acceptable
range ( valve_flow_OK = True).
• ERROR: Valves are disabled - Check BattVolt is displayed if the
battery voltage has dropped below the minimum and the CPEC200
has disabled the valves. This correlates with BattVolt_OK = False.
See notes for bit 9.
• ERROR: Valves are disabled - IRGA is OFF is displayed if the
CPEC200 has disabled the valves because the IRGA is off. This
correlates with irga_OFF = True and could be a result of the EC155
automatically powering down because its source temperature is
outside operating range. See the EC155 CO
2
and H
2
O Closed-Path
Gas Analyzer Manual for details.
• ERROR: press_offset is zero - turn pump off and set DO_P_offset =
true is displayed if press_offset = 0. The CPEC200 requires a recent
measurement of the pressure offset which is given as the sample cell
pressure measured with no flow. The pressure offset is set to zero
when it is no longer valid. A new measurement of the pressure offset
can be achieved by turning, the pump off and setting DO_P_offset =
True. See Section 4.2.3, Valve Module, for more details on how the
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