Campbell Scientific CPEC200 Closed-Path Eddy-Covariance System - Manual (Page 45)

CPEC200 Closed-Path Eddy-Covariance System
TABLE 6-1. Automatic Zero/Span Sequence
Step Mode Status Pump
valve_number
Duration (sec) Keypad Value
1 Measuring Pressure Off None 0 10
2 Checking CO2 Span 1 Off CO2span1 2 SPAN_TIME
3 Checking Zero Off ZeroAir 1 ZERO_TIME
4 Setting Zero Off ZeroAir 1 10
5 Rechecking CO2 Span 1 Off CO2span1 2 SPAN_TIME
6 Setting CO2 Span 1 Off CO2span1 2 10
7 Checking CO2 Span 2 Off CO2span2 3 SPAN_TIME
8 Checking CO2 Span 3 Off CO2span3 4 SPAN_TIME
9 Checking CO2 Span 4 Off CO2span4 5 SPAN_TIME
10 Equilibrating for EC On None 0 10
11 Switching to EC mode On None 0 0.1
6.3 Manual Zero and Span
There are two ways to manually zero/span the IRGA in the CPEC200:
1. The zero/span sequence may be run at any time by initiating the
sequence manually. This will often be the easiest way to do a manual
zero/span, but the sequence cannot do the H
2
O span. At the
completion of the sequence the system will automatically return to EC
mode.
2. The user may manually control each step in the zero/span process.
Using full manual control allows the H
2
O to be spanned. It also
bypasses some of the automated checking. For example, full manual
control will allow the user to do a zero or span even if there is a
diagnostic flag.
The two approaches to doing a manual zero/span are described below:
6.3.1 Manually starting the zero/span sequence
6.3.1.1 Temperature Control
Both the valve and scrub modules have heaters and fans to keep them within
their operating temperature range. Generally, this temperature control function
is disabled to conserve power. If the CPEC200 is configured for automatic
zero/span sequences, it will automatically enable temperature control of the
valve and scrub modules before the zero/span sequence is scheduled to begin.
This allows the valve module and scrub module to reach operating temperature
range even in very cold weather.
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