ED15117
63
Alarms-BACnet
Alarm Classes
BACnet alarms in a Magnitude Chiller Unit Controller are divided into three classes: Faults, Problems,
and Warnings. Fault alarms have the highest severity level. Problem alarms have medium severity
level. Warning alarms have the lowest severity level.
Fault Alarms
Fault alarms require an acknowledgment from the operator. These alarms indicate that the compressor
is shut down.
Problem Alarms
Problem alarms do not cause compressor shutdown but limit operation of the chiller in some way.
Warning Alarms
A warning is enunciated whenever an abnormal condition exists which does not affect chiller operation.
BACnet Alarm Handling
The BACnet Communication Module has two methods for handling BACnet alarms: Monitor by
Alarm Class, and Alarm Digital Output.
Monitor by Alarm Class
The Monitor by Alarm Class method requires that three Analog Value objects in the BACnet
Communication Module be polled for alarm notification. One object indicates Warning Alarms, one
indicates Problem Alarms, and one indicates Fault Alarms. The Analog Value objects return a number
for an alarm condition. The number is found in the Index column of Table 8.
Alarm Warnings
This BACnet object indicates the index number of warning alarms. If the present value is zero, no
alarm has occurred. See Table 8.
Measurement
Units
Data Type
Valid Range
Default Value
NA NA Integer
Enumerated
NA
Object Identifier
Property Identifier
Object Type
Type Enumeration
Instance
Property Name
Property Enumeration
Analog Value
2
902
Present Value
85
Object Name
AVWarningAlarm
Alarm Problems
This BACnet object indicates the index number of problem alarms. If the present value is zero, no
alarm has occurred. See Table 8.
Measurement
Units
Data Type
Valid Range
Default Value
NA NA Integer
Enumerated
NA
Object Identifier
Property Identifier
Object Type
Type Enumeration
Instance
Property Name
Property Enumeration
Analog Value
2
900
Present Value
85
Object Name
AVProblemAlarm
