BACnet Data Address

Introduction

Data in BACnet Devices is stored in objects and properties.

The BACnet Data Address is a string that defines the location of a property in a BACnet device. The string uses the following format:

bacnet-data-address ::=
object-ref '.' property-ref [ . bit-ref ]

object-ref ::=
{ object-name-identifier | object-name-string | object-type ':' object-instance }

object-type ::=
{ identifier | unsigned-integer-value }

property-ref ::=
{ property-name | property-identifier }

bit-ref ::=
unsigned-integer-value

Where:

object-name-identifier is the name of an object as an identifier, for example Door15.
object-name-string is the name of an object as a string, for example 'Door 15'.
object-type is the type of an object, for example Analog_Output, or 1.
object-instance is the instance number of an object.
property-name is the name of the property of the object.
property-identifier is a property identifier as a number.
bit-ref is an optional bit number reference to select a bit from a bit string.

Examples

Example	Comment
Temperature.Present_Value	The Present_Value property of an object called Temperature
'Input 15'.Present_Value	The Present_Value property of an object called Input 15
Device.Description	The Description property of an object called Device
Analog_Input:1.Present_Value	The Present_Value property of an analog input with instance number 1.
176:1.Present_Value	The Present_Value property of instance number 1 of custom object type 176.
Binary_Input:5.Status_Flags.1	The Fault bit of the Status_Flags property of Binary Input instance number 5.

Object Types

You can use these values for object-type:

Object Type	Description
Access_Door	A door to access an area of a building
Analog_Input	An analog input
Analog_Output	An analog output
Analog_Value	Internally stored analog value
Averaging	Samples minimum, maximum and average value
Binary_Input	A binary or digital Input
Binary_Output	A binary or digital Output
Binary_Value	An internally stored binary value
Calendar	A list of calendar dates
Command	A set of commands on objects
Device	A BACnet device
Event_Enrollment
Event_Log	Stores a log of event records
Group
Load_Control
Life_Safety_Point
Life_Safety_Zone
Loop
Multi_State_Input	An input with multiple bits
Multi_State_Output	An output with multiple bits
Multi_State_Value	An internally stored value with multiple bits
Notification
Program
Pulse_Converter	A counter for pulses
Schedule
Structured_View	Organizes objects in a hierarchy
Trend_Log	Stores a property historically
Trend_Log_Multiple	Stores multiple properties historically

Where Used

The BACnet Data Address is used in these contexts:

In the IOItemName property of an I/O Analog Data Point Tag when the tag is associated with a BACnet Device.
In the IOItemName property of a I/O Digital Data Point Tag when the tag is associated with a BACnet Device.
In the IOItemName property of a I/O Word Data Point Tag when the tag is associated with a BACnet Device.
In the IOItemName property of a I/O Double Word Data Point Tag when the tag is associated with a BACnet Device.
In the IOItemName property of a I/O Long Word Data Point Tag when the tag is associated with a BACnet Device.
In the IOItemName property of a I/O String Data Point Tag when the tag is associated with a BACnet Device.

Further Information

BACnet Driver

For an overview of the BACnet Driver.

Glossary

For the meaning of terms used in Fernhill SCADA.