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LNS Programmer's Guide

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property values to the device, call the DownloadConfigProperties() method with the

lcaConfigPropOptLoadValues and lcaConfigPropOptExcludeDeviceSpecific

options set.

For more information on the UploadConfigProperties() and

DownloadConfigProperties() methods, see Downloading and Uploading

Configuration Properties on page 126.

Using the GetDataPoint Method

You can use a DataPoint object to read and write to the value of a configuration

property. Each data point has three properties you can use to read and write to the data

point’s value: the FormattedValue property, the RawValue property, and the Value

property. Each of these properties represents the same value, but each one is formatted

differently:

• The Value property formats the data as a scaled, double float value. The

configuration property’s type file must be available in order to read the

Value property.

• The FormattedValue property formats the data based on the LNS

Object Server’s CurrentFormatLocale setting. The data stored in the

FormattedValue property is scaled and unit-converted based on the

FormatSpec the data point is using. The configuration property’s type

and formats file must be available in order to read the FormattedValue

property. For more information on FormatSpec objects, see Data

Formatting in page 241.

• The RawValue property formats the data as a raw byte array.

Depending on how you set the options element when you call GetDataPoint() to

create a DataPoint object for a configuration property, LNS may read or write the LNS

database, the configuration property on the physical device, or both when you read or

write the value of the DataPoint. This is described in more detail later in this section.

To acquire a DataPoint to use to read and write the value of a configuration property,

follow these steps:

1. Access the ConfigProperty you want to monitor and control. In this

example, the configuration property “cpCalibration” applies to the device

as a whole. Some configuration properties apply to a LonMark

Functional Block or network variable, in which case they are accessed via

the ConfigProperties collection of the parent LonMarkObject or

NetworkVariable.

Set MyInterface = myAppDevice.Interface

Set MyConfigProperties = MyInterface.ConfigProperties

Set MyCP = MyConfigProperties.Item(“cpCalibration”)

2. Call the GetDataPoint() method to create a DataPoint object for the

ConfigProperty.

Set MyDataPoint=MyCP.GetDataPoint(0,lcaDataSourceOptionsNormal)

Some configuration properties are arrays of elements. In this case, you

need to create a separate data point to read and write to each element in

the array. The first parameter passed to the GetDataPoint() method is

the index parameter. This specifies which element of the array you want

this data point to apply to. These arrays are 0-based. If the

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