Part
2. Functional Specifications
50
Design Guide
DCM014A51
7. Detailed Description of Objects
7.1 Specifications Common to All Objects
For each communication status of an indoor unit, objects related to that indoor unit
and
system control device
are treated in
BACnet
as follows:
1. Indoor unit communicating normally
Other
BACnet
devices can access all objects for the indoor unit.
The value of the following properties of each object at this point is as follows:
Reliability: NOFAULT_DETECTED
FAULT flag of the Status_Flags property: FALSE
2. Indoor unit communication in error
Although other
BACnet
devices can access objects for the indoor unit, requests for
Present_Value readout returns values immediately before the communication error.
If the aforementioned value is undetermined, 0 is returned for AI, Inactive for BI, and 1 for MI.
Objects of type Output and Value follow the value of Relinquish_Default property.
Furthermore, the value of the following properties for objects other than the communication
status object at this point is as follows:
Reliability: UNRELIABLE_OTHER
FAULT flag of the Status_Flags property: TRUE
When issued during a communication error, commands are not sent out to the
VRV
communication line (DIII network).
Note 1
: In the indoor unit, the setpoints, start/stop status, mode, airflow direction, and fan
speed are written to the non-volatile memory each time they are changed so the settings are
not lost in the event of a power failure.
The number of times this non-volatile memory can be written is limited, and writing beyond
that limit may cause failure to the indoor unit EEPROM. This will not cause the indoor unit to
stop functioning; however, the volatile memory will not retain the last settings received.
Consequently, when the setpoints, start/stop status, dependent mode, airflow direction, and
fan speed are frequently changed by automatic control from the BMS, the number of times
each setting for each indoor unit is limited to 70,000 – 80,000 times per year (dependent on
the indoor unit manufacturing date).
3
.
Outdoor unit communicating normally
Other
BACnet
devices can access to all objects for the outdoor unit.
The values of the following properties of each object at this point are as follows.
Reliability: NOFAULT_DETECTED
FAULT flag of the Status_Flags perperty: FALSE
4. Outdoor unit communicating in error
Although other
BACnet
devices can access objects for the outdoor unit, requests for
Present_Value readout return values immediately before the communication error.
If the aforementioned value is undetermined, 0 is returned for AI, Inactive for BI, and 1 for MI.
Furthermore, the value of the following properties of objects other than communication status
object at this point is as follows.
Reliability
:
UNRELIABLE_OTHER
FAULT flag of the Status_Flags property:
TRUE