Campbell-scientific CR9000X Measurement and Control System Uživatelský manuál stáhnout pdf (Strana 167)

Section 4. CRBasic – Native Language Programming

4.3 Program Access to Data Tables

Data stored in a table can be accessed from within the program. The format

used is:

Tablename.Fieldname_PRC( index,recordsback)

Where

Tablename The name of the table in which the desired value is stored. The

table can be a user defined table or the Status table.

Fieldname The name of the field in the table and is always an array even if

it consists of only one variable.

_PRC Abbreviation for the field processing used in the storage

process. For example, PRC = AVG when the Average data

processing instruction is used. Do not use an _PRC for Sample

processing, or for retrieving data from the Status Table. See

Table 4.3-1 for a list of these abbreviations.

Index Specifies the array element from which to retrieve the data and

must always be specified. Use 1 if the FieldName is a single

element array.

Recordsback The number of records back in the data table from the current

time (1 is the most recent record stored, 2 is the record stored

prior to the most recent) to retrieve. A negative number can be

entered for the RecordsBack parameter to specify the time, in

seconds since 1990.

A use example for this syntax would be to calculate the change in an average

output between two records. For Example Program 4.2.10-2, to find the change

in the 100 millisecond average between the most recent average and the average

that was stored 101 records earlier for TC(1), you could insert following code

into the program:

Tdiff=Table1.TC_Avg(1,1)–Table1.TC_Avg(1,101)

TABLE 4.3-1 Output Processing Abbreviations

PRC

Abbreviation

Output

Processing Name

PRC

Abbreviation

Output

Processing Name

Avg Average

MMT Moment

Cov Covariance

RFH RainFlow Histogram

Etsz ET

Rso Solar Radiation

FFT FFT

None required Sample

H4D Histogram4D

SMM Sample at Max or Min

Hst Histogram

Std Standard Deviation

LCr Level Crossing

TMx Time of Max

Max Maximum

TMn Time of Min

Med Median

Tot Totalize

Min Minimum

WVc WindVector

If a time of minimum or maximum is returned by Tablename.Fieldname, the

time is reflected in seconds since 1990. However, if FieldNameIndex is entered

as a negative value, then time is reflected in usec since 1990. This time value

can be converted to a standard datalogger timestamp if the variable is declared

as a Long and is Sampled into a table using the NSEC data format.

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