Daikin McQuay ED 15117 Protocol Information Download

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ED15117

(read/write properties, e.g., setpoints) from the network and others can only be interrogated (read-only
properties, e.g., status information).

Each data point accessible from a BACnet network is described with a table that gives the Object
Identifier, Property Identifier, Full BACnet Reference or path, and the Name enumeration of the
property.

Example of BACnet Data Point

Object Identifier

Property Identifier

Object Type

Type Enumeration

Instance

Property Name

Property Enumeration

Binary Output

Present Value

Object Name

AlarmDigitalOutput

Property Values

0 = No Alarm
1 = Alarm

Object Identifier

Object Identifiers are each designated with an Object type as defined in the BACnet specification. The
first column of the data point definition gives the object type. This object happens to be Alarm Digital
Output. The object identifier is a property of the object that you can read from the object. The name of
the property is “Object_Identifier” and the property identifier is 75.

Each object in the unit controller has a unique identifier. BACnet object identifiers are two-part
numbers of BACnet Object Identifier data type. The first part identifies the object type (the first 10 bits
of the 32-bit BACnet Object Identifier [See ANSI/ASHRAE 135-2004 BACnet A Data
Communication Protocol for Building Automation and Control Networks]). The first column of the
data point definition gives the object type. The second part identifies the instances of that particular
object type (the last 22 bits of the 32-bit BACnet Object Identifier).

The object identifier is shown in the data points listing as two numbers. The first number is shown in
the Type ID column and designates the Object type enumeration. The second number is shown in the
Instance column and designates the instance of that particular object type.

The object identifier is a property of the object that you can read from the object code. The name of the
property is “Object_Identifier” and the property identifier is 75. The ASHRAE BACnet specification
reserves the first 128 numbers for ASHRAE defined objects. Manufacturers may define additional
object types and assign a number above 127 as long as they conform to the requirements of the
ASHRAE BACnet specification.

Each object also has a name. Object Names are character strings. The object name is a property of the
object that you can read from the object. The name of the property is “Object_Name” and the property
identifier is 77.

Objects are sometimes referred to as an Object Type and Instance Number as they are in the BACnet
specification. The example object above would be: Binary Output, Instance 5.

Property Identifier

Each object has a number of properties or attributes. Each property has a unique identifier of BACnet
Property Identifier data type. Property identifiers are an enumerated set; a number identifies each
member. The Property Identifier enumeration number is shown in the Property ID column. In the
example above the property identifier is 85.