Campbell Scientific CS110 Electric Field Meter - Manual (Page 33)

CS110 Electric Field Meter
accomplished using a disable variable (DisableVar) associated with
appropriate output processing instructions. The last parameter of the Average
instruction is the DisableVar and will exclude the current measured value
when DisableVar is not equal to zero. In order to prevent a single NAN
electric field result from corrupting measurements over the entire output
interval, the variable meas_error is used to disable writing NAN results to the
Average(1,E_field,ieee4,meas_error) instruction in TabSlow.
It is also sometimes desirable to keep a count of total measurement errors,
which is accomplished in the above program by the variable Error_Count. The
last stored value of Error_Count is retrieved from final storage at the beginning
of the program and Error_Count is incremented once during a scan each time
status >6 from the CS110 instruction. The Error_Count can be zeroed by
means of LoggerNet by accessing the Public variable Error_Count in the
Numeric display available in the Connect Screen.
Appendix F contains more example CS110 programs that users may find
beneficial in various applications. A more detailed description of CRBasic is
contained in the CR1000 Measurement and Control System Operator’s
Manual.
8. CS110 Measurement Instructions
8.1 CR1000 Measurement Overview
The CR1000 datalogger can perform many different measurement tasks as
defined by measurement instructions in CRBasic. A brief explanation of
CS110 measurement instructions is given followed by some specific examples.
Further measurement instructions and measurement details are provided in the
CR1000 Measurement and Control System Operator’s Manual.
The CR1000 differential voltage measurement (VoltDiff) instruction is given
as follows:
VoltDiff(Dest,Reps,Range,DiffChan,RevDiff,Settling Time,Integ,Mult,Offset)
where Dest is the destination variable of the result. Reps is the number of
times to repeat a given measurement on successive channels, Range is one of
±5000 mV, ±2500 mV, ±250 mV, ±25 m, ±7.5 mV, or ±2.5 mV input voltage
ranges available on the CR1000. DiffChan is the appropriate differential input
channel (1 – 8). RevDiff is a true or false parameter to determine whether or
not to perform two successive differential measurements with reversed input
polarity, in order to reduce low-frequency measurement errors. Settling Time
is a parameter allowing extra input settling time for “slow” settling sensors.
Integ is a parameter indicating the length of time to perform an analog
integration during the measurement, with options of 250
μs, _50Hz and _60Hz.
Integration times for _50Hz and _60Hz are 20 ms and 16.67 ms, respectively
for cancellation of unwanted 50 Hz and 60 Hz noise. Mult provides for scaling
within the measurement instruction, while Offset provides for the
incorporation of offsets.
25