Campbell-scientific CR3000 Micrologger Manuel d'utilisateur télécharger pdf (Page 344)

Section 8. Operation

344



willberepresentedbyfourfieldnames:“values(1,1)”,“values(1,2)”,

“values(2,1)”,and“values(2,2)”.Scalar(non‐array)variableswillnot

havesubscripts.

Line 3 – Data Units

Includestheunitsassociatedwitheachfieldintherecord.Ifnounits

areprogrammedintheCR3000CRBasicprogram,anemptystringis

enteredforthatfield.

Line 4 – Data-Processing Descriptors

EntriesdescribewhattypeofprocessingwasperformedintheCR

3000

toproducecorrespondingdata,e.g.,Smpindicatessamples,Min

indicatesminima.Ifthereisnorecognizedprocessingforafield,itis

assignedanemptystring.Therewillbeonedescriptorforeachfield

namegivenonHeaderLine2.

Record Element 1 – Timestamp

Datawithoutti

mestampsareusuallymeaningless.Nevertheless,the

TableFile()instructionoptionallyincludestimestampsinsomeformats.

Record Element 2 – Record Number

Recordnumbersareoptionallyprovidedinsomeformatsasameansto

ensuredataintegrityandprovideanup‐countdatafieldforgraphing

operations.Themaximumrecordnumberis&hffffffff(a32‐bit

number),thenthere

cordnumbersequencerestartsatzero.The

CR3000reportsbacktothedataloggersupportsoftware31bits,ora

maximumof&h7fffffff,thenitrestartsat0.Iftherecordnumber

incrementsonceasecond,restartatzerowilloccuraboutonceevery

68years.

8.3.2 Memory Conservation

One or more of the following memory-saving techniques can be used on the rare

occasions when a program reaches memory limits:

• Declare variables as DIM instead of Public. DIM variables do not require

buffer memory for data retrieval.

• Reduce arrays to the minimum size needed. Arrays save memory over the

use of scalars as there is less "meta-data" required per value. However, as a

rough approximation, 192000 (4-kB memory) or 87000 (2-kB memory)

variables will fill available memory.

• Use variable arrays with aliases instead of individual variables with unique

names. Aliases consume less memory than unique variable names.

• Confine string concatenation to DIM variables.

• Dimension string variables only to the size required.

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Campbell-scientific CR3000 Micrologger Manuel d'utilisateur Page 344

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