Echelon LNS Manuel d'utilisateur télécharger pdf (Page 250)

LNS Programmer's Guide

236

ConfigProperty is not an array, specify 0 as the index parameter.

The second parameter is the options element. This determines how

LNS will apply changes you make to the DataPoint object to the LNS

database, and to the physical device on the network. For more

information on this, see the next section, Data Source Options.

Note that you can change both of these options later by modifying the

DataPoint object’s SourceIndex or SourceOptions properties.

3. To set the value of the configuration property through the DataPoint

object, set the Value, RawValue or FormattedValue property, and

then call the Write() method. Note that you do not need to call Write()

if the AutoWrite property is set to True.

MyDataPoint.Value = 1000

MyDataPoint.Write()

NOTE: The Value, RawValue and FormattedValue properties of

DataPoint objects acquired through configuration properties that use

enumerated data types have special behavior that you should be aware

of. For more information, see Data Points and Enumerated Types on page

232.

4. To read the value of the configuration property through the DataPoint

object, call the Read() method and then read the value through the

Value or FormattedValue properties. You do not need to call Read() if

the AutoRead property is set to True.

Dim Value as String

MyDataPoint.Read()

value = MyDataPoint.FormattedValue

When reading a DataPoint object’s value, there are many ways for the

application to affect how the data will be displayed. For more information

on this, see Data Formatting on page 241.

NOTE: Data points are very useful when reading and writing formatted data, or when

accessing an entire raw data value as a whole. However, if you want to access arbitrary

bytes of raw data to read or write a range of elements in a configuration property array,

you should not use a data point. Instead, you should use the GetRawValuesEx() and

SetRawValuesEx() methods of the ConfigProperty object. See the LNS Object Server

Reference help file for more information on these methods.

Data Source Options

When you call the GetDataPoint() method, you will use the options parameter to

specify how LNS will manage differences that may exist between the value of the

ConfigProperty in the LNS database and the value of the configuration property in the

physical device on the network when you read or write to the DataPoint. Table 9.4

describes the values you can apply to the options element.

Note that the value you choose as the options parameter is stored in the DataPoint

object’s DataSourceOptions property. If desired, you can change this setting later.

1 2 ... 245 246 247 248 249 250 251 252 253 254 255 ... 367 368

Commentaires sur ces manuels

Pas de commentaire

Echelon LNS Manuel d'utilisateur Page 250

Commentaires sur ces manuels

Produits connexes et manuels pour Logiciel Echelon LNS