Campbell CR800 Specifications download pdf (Page 102)

Section 4. CRBasic - Native Language Programming

Average is an output processing instruction that will output the average of a

variable over the output interval. The parameters are repetitions - the number

of elements in an array to calculate averages for, the Source variable or array to

average, the data format to store the result in (Table 4.3-1), and a disable

variable that allows excluding readings from the average if conditions are not

met. A reading will not be included in the average if the disable variable is not

equal to 0; the example has 0 entered for the disable variable so all readings are

included in the average.

TABLE 4.3-1 Formats for Output Data

Code Data Format Size Range Resolution

FP2 Campbell Scientific floating point 2 bytes

±7999

13 bits (about 4 digits)

IEEE4 IEEE four byte floating point 4 bytes 1.8 E -38 to 1.7 E 38 24 bits (about 7 digits)

LONG 4 byte Signed Integer 4 bytes -2,147,483,648 to

+2,147,483,647

1 bit (1)

BOOLEAN 4 byte Signed Integer 4 bytes 0, -1 True or False (-1 or 0)

STRING ASCII String Set by

programmer

4.3.2 The Scan -- Measurement Timing and Processing

Once you know what you want, the measurements and calculations have been

listed and the output tables defined, the program itself may be relatively short.

The executable program begins with BeginProg and ends with EndProg. The

measurements, processing, and calls to output tables bracketed by the Scan and

NextScan instructions determine the sequence and timing of the datalogging.

BeginProg

Scan(1,Sec,3,0)

ModuleTemp(RefTemp, 250)

TCDiff(TC(),6,mV2_5C,4,1,TypeT,RefTemp,RevDiff,Del,Integ,Mult,Offset)

CallTable Temp

NextScan

EndProg

The Scan instruction determines how frequently the measurements within the

scan are made:

' Scan(Interval, Units, BufferSize, Count)

Scan(1,Sec,3,0)

The Scan instruction has four parameters. The Interval is the interval between

scans. Units are the time units for the interval. The minimum interval is 10

milliseconds. The maximum scan interval is 30 minutes. The BufferSize is the

size (in the number of scans) of a buffer in RAM that holds the raw results of

measurements. Using a buffer allows the processing in the scan to at times lag

behind the measurements without affecting the measurement timing (see the

scan instruction in Section 9 for more details). Count is the number of scans to

make before proceeding to the instruction following NextScan. A count of 0

means to continue looping forever (or until ExitScan). In the example the scan

4-6

1 2 ... 97 98 99 100 101 102 103 104 105 106 107 ... 323 324

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Campbell CR800 Specifications Page 102

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