Campbell Scientific CPEC200 Closed-Path Eddy-Covariance System - Manual (Page 58)

Appendix A. CPEC200 Diagnostics
pressure sensor is used to infer flow, and Section 6.3.2, Full Manual
Control of Zero and Span, for more detailed information about how
the pressure offset is measured.
• ERROR: Valve flow is NAN is displayed if press_offset is not zero
and valve _flow = NAN (see the note above for the case when
press_offset = 0). This indicates a problem with the valve flow
measurement. See notes on bit 3 for details.
• ERROR: Valve flow is not at setpoint - Check buff_depth is displayed
if the valve flow is outside the acceptable range ( valve_flow_OK =
False) and the processing has fallen too far behind (buff_depth_OK
= False). A processing delay does not always cause a valve flow
error. In some cases, the processing may catch up before the valve
flow drifts too far from the setpoint. For additional information see
notes on bit 4.
• ERROR: Valve flow is not at setpoint is displayed if the valve flow is
outside the acceptable range and the problem cannot be explained by
one of the conditions listed above. For additional troubleshooting
advice, see notes on bit 3.
A.3 Status Boolean Variables
CPEC200 status information is also provided as discrete Boolean variables that
indicate whether or not a particular subsystem has a problem. Most of these
variables have names that end in “OK.” These variables are intended to bridge
the gap between the user-friendly “status text variables” and the compact yet
cryptic “diagnostic words.” They provide an intermediate level of information
for real-time troubleshooting and allow the CPEC200 to store statistics on
various conditions.
EC_mode
This Boolean variable is intended for screening time-series data for post-
processing. EC_mode = True if the sample pump is on and no zero/span
sequence is running (see Section A.2, Status Text Variables). Records for
which EC_mode = False, should be excluded from EC calculations. This
variable is also used by the CPEC program to determine the relevance of some
of the error conditions. For example, the pump flow is relevant only in EC
mode, but the battery voltage is always relevant. This relevance based on
EC_mode determines whether or not a particular bit will be set in diag_cpec
(see Section A.2, Status Text Variables, for details).
BattVoltOK
Boolean variable BattVoltOK is equivalent to bit 9 of diag_cpec. If
BattVoltOK is false, this indicates the CPEC200 supply voltage has fallen
below the shutdown limit and has not risen to an acceptable restart level. See
notes on bit 9.
irga_OK
Boolean variable irga_OK is equivalent to bit 8 of diag_cpec. If an IRGA
problem is detected, irga_OK = False and bit 8 of diag_cpec will be set. See
notes on bit 8 and on irga_status, which may give additional information
about the IRGA problem.
sonic_OK
Boolean variable irga_OK is equivalent to bit 8 of diag_cpec. If an IRGA
problem is detected, irga_OK = False and bit 8 of diag_cpec will be set. See
A-6