BACnetX ActiveX Component - Object Access Tutorial

Introduction

To Access Objects in BACnet there are services such as readProperty, readPropertyMultiple, writeProperty and writePropertyMultiple. This tutorial demonstrates how to use the readProperty and writeProperty services with the BACnetX activeX component.

Create a global ApplicationLayer object


Public objApplicationLayer As BACNETXLib.ApplicationLayer

Initialize the Application Layer Object


Set objApplicationLayer = New BACNETXLib.ApplicationLayer
objApplicationLayer.Initialize 200

Issue a Read Property Request


Dim Service As New ReadProperty

Service.DeviceID = 100
Service.Request.objectIdentifier.Instance = 1
Service.Request.objectIdentifier.ObjectType = BACnetObjectTypeAnalogValue
Service.Request.propertyIdentifier = Property_presentValue
Service.Execute

If Service.Error.choice = BACnetErrorChoiceEmpty Then
	Debug.Print "Value = " & Service.Ack.propertyValue.Real
Else
	Debug.Print "Error Class = " & Service.Error.Error.Class & " Error Class = " & Service.Error.Error.Code
End If

Issue a Write Property Request


Dim Service As New BACNETXLib.WriteProperty

Service.async = False
Service.DeviceID = LocalDeviceID
Service.Request.objectIdentifier.Instance = 1
Service.Request.objectIdentifier.ObjectType = BACnetObjectTypeBinaryValue
Service.Request.propertyIdentifier = Property_presentValue
Service.Request.priority = 8 'Priority 8 for Manual Overides
Service.Request.propertyValue.Enumerated = BACnetBinaryPVActive
Service.Execute

If Service.Error.choice <> BACnetErrorChoiceEmpty Then
	Debug.Print "Error Class = " & Service.Error.Error.Class & " Error Class = " & Service.Error.Error.Code
End If

Source Code

The Source Code for this application is avaliable as part of the BACnetX ActiveX component from the downloads area of this web site.

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