Campbell Scientific CPEC200 Closed-Path Eddy-Covariance System - Manual (Page 69)

Appendix A. CPEC200 Diagnostics
table ts_data, the state of fans and heaters is encoded into variable
ControlBits to conserve memory space. See Appendix D, Control Bits. This
value is saved only if saving all diagnostics. Its corresponding variable
valve_heat_Avg is saved in the averaged output tables (Flux and Zero_Span).
If the heater is on and the valve module is too cold, check the ambient
temperature. The CPEC200 is rated for temperatures from −30°C to 50°C. If
the system is started in cold weather after being turned off for several hours, it
may take up to 15 minutes to warm up to operating temperature.
The valve module will also be disabled if it is too warm (above 60°C). The
valve module has a fan that turns on if valve_tmpr rises above 50°C. The fan
will stay on until the valve temperature falls below 48°C. If the valve module
temperature is too high, check the operation of the fan which is controlled by
public variable valve_fan_ON. For diagnosing a problem using data saved in
the output table ts_data, the state of fans and heaters is encoded into variable
ControlBits to conserve memory space. See Appendix D, Control Bits. This
value is saved only if saving all diagnostics. Its corresponding variable,
valve_fan_Avg, is saved in the averaged output tables (Flux and Zero_Span).
If the fan is on and the valve module temperature is too high, check the
ambient temperature. The CPEC200 is rated for ambient temperatures between
–30°C to 50°C.
Bit 1: Scrub Module Temperature
If the remainder of diag_cpec (after subtracting the numeric value for higher
bits that are set) is equal to one, this means that bit 1 of diag_cpec is set.
Bit 1 of diag_cpec indicates the scrub module temperature is outside its
operating range. This check is performed only if the CPEC200 program is
configured to use a scrub module. In that case, this check is performed all the
time, and Boolean variable, scrub_tmprOK, is set accordingly. However, the
scrub module temperature is ignored in EC mode (bit 1 of diag_cpec is set
only if it is relevant). If the scrub module is within its operating range the
scrub module pump is turned on any time the Zero Air valve is selected. If the
scrub module is outside its operating range the zero/span sequence cannot be
run, and the Zero Air valve (1) cannot be selected manually. This protects the
scrub module pump from possible damage.
To confirm the problem, verify that public variable scrub_tmprOK = False.
This variable is set to True if the scrub module temperature is within its
operating range (5°C to 50°C) and is set to False if it is outside this range.
The variable scrub_tmprOK is not available for diagnosing a problem using
data saved in the output tables ( Flux or Zero_Span). Instead, check the value
of ScrubTmprOK_Avg. This is a floating point number that represents the
fraction of time (from 0 to 1) that scrub_tmprOK is true during the averaging
period. A value of 1 indicates no scrub module temperature problem at any
time during the averaging period. A value of 0 indicates a scrub module
temperature problem during the entire time.
To continue troubleshooting a problem with the scrub module temperature,
check the measured temperature, scrub_tmpr. If it is NAN, this indicates a
problem with the temperature measurement. Make sure the scrub module cable
is connected to the Scrub Module connector on the bottom of the CPEC200
system enclosure.
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