Property Name
Each property also has a unique name. Property names are character strings and shown in the Property
Name column. In the example above the property name is Present Value.
Object Name
The Object Name is the name of the object in the device. Object Names must be unique within each
BACnet device. In the example above the object name is AlarmDigitalOutput.
Enumerated Values
Some properties are standard data types and some are enumerated sets. If the property value is an
enumerated set, all enumerated values and corresponding meaning are given in the Enumeration
column of the data point listing.
Magnitude Chiller Unit Controller Device Object
Each BACnet-compatible device can only have a single BACnet Device Object.
Device Object Identifier
The Magnitude Chiller Unit Controller Device Object Identifier uniquely specifies the unit within the
network. The device object type for all devices is fixed by ASHRAE at 8. Therefore the device object
instance number must be unique. The device object instance will be read from a parameter in the
Magnitude Chiller Unit Controller during the BACnet communication module’s initialization phase.
The BACnet communication module continues to poll the device object instance parameter during run-
time. If the device object instance is changed at the controller during run-time, the update will be
automatically applied to the BACnet communication module as soon as the change is received. The
allowable range of values for the device object instance will be 0 to 4194302. (The value 4194303 is
reserved by BTL for reading a device’s object id.) If a value greater than 4194302 is read from the
controller, the following default value will be used:
Default device object instance:
3000 + address*
*
Address
= the last two octets of the MAC Address
For example:
BACnet MS/TP:
3023
BACnet Ethernet: 10312 (3000 + F75A)
BACnet/IP: CDB (3000 + 0123)
The device object identifier can be read from the unit controller. The name of the property is
“Object_Identifier” and the property identifier is 75. Changing the device object ID may affect the
operation of other BACnet devices on the network that have previously discovered the device. The
object instance number can be changed via the unit controller OITS panel.
!
CAUTION
If another device in the network already has this object identifier (instance number), you must change the instance number of one
device object, so that all devices in the network have a unique device identifier.
Device Object Name
The Device Object Name uniquely specifies a device in the network. It must be unique in the network.
The device object name will be read from a parameter in the Magnitude Chiller Unit Controller during
the BACnet communication module’s initialization phase. The BACnet communication module
continues to poll the device object name parameter during run-time. If the device object name is
changed at the controller during runtime, the update will be automatically applied to the BACnet
8
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