7 BACnet Communication
3-100
WindO/I-NV4 User’s Manual
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Subscribed COV (COV) function
In the COV (Change Of Value) function, the MICRO/I monitors an object for which a report request has been received
from a BACnet device. Then when Present_Value or Status_Flags has changed, the MICRO/I notifies the BACnet
device of the change.
The properties of objects that correspond to the COV function and the timing of when to provide notification of
changes are given as follows.
*1 For example, the following diagram shows when a report request is received from a BACnet device and AI-10 (Analog Input
object, instance number 10) has the status in the following table.
Object
Properties
Timing to Provide Notification of Change
Analog Input
Analog Output
Analog Value
Present_Value
Status_Flags
Notification of change is provided when (1) or (2) as follows.
(1)
When Present_Value has changed to a value greater than or equal to the value
set for COV_Increment (starting point is from when the previous COV
notification was sent)
(2) When any of the bits in Status_Flags have changed
Binary Input
Binary Output
Binary Value
Present_Value
Status_Flags
Notification of change is provided when (1) or (2) as follows.
(1) When Present_Value has changed
(2) When any of the bits in Status_Flags have changed
Notification may not be provided for changes in values that are faster than the synchronization cycle of
objects and device addresses.
AI-10 Properties
Value
Present_Value
10.0
COV
_Increment
3.0
BACnet device
MICRO/I
Report request
COV notification
transmission
(To report requester)
Present_Value of AI-10
has changed to 15.0.
COV notification
transmission
Present_Value of AI-10
has changed to 18.5.
Present_Value of AI-10: 10.0
COV_Increment: 3.0
Present_Value of AI-10 has changed to 15.0
(Change in Present_Value (5.0) > COV_Increment (3.0))
This change corresponds to timing to provide notification of change (1).
Change in Present_Value = Present value - Value when report request
was received = 15.0 - 10.0 = 5.0
Because COV_Increment = 3.0,
change in present value ≥ COV_Increment has been satisfied.
Present_Value of AI-10 has changed to 17.5
(Change in Present_Value (2.5) > COV_Increment (3.0))
Change in Present_Value = Present value - Value when previous
COV notification was transmitted = 17.5 - 15.0 = 2.5
Change in Present_Value < COV_Increment, and the condition
for timing to provide notification of change (1) is not satisfied.
Therefore, COV notification is not sent.
Present_Value of AI-10 has changed to 18.5
(Change in Present_Value (3.5) > COV_Increment (3.0))
This change corresponds to timing to provide notification of change (1).
Change in Present_Value = Present value - Value when previous
COV notification was transmitted = 18.5 - 15.0 = 3.5
Because COV_Increment = 3.0,
Change in Present Value ≥ COV_Increment has been satisfied.
Summary of Contents for WindO/I-NV4
Page 1: ...B 1701 16 User s Manual...
Page 108: ...5 WindO I NV4 Common Operations and Settings 2 76 WindO I NV4 User s Manual...
Page 256: ...7 BACnet Communication 3 148 WindO I NV4 User s Manual...
Page 372: ...6 Screen Restrictions 5 32 WindO I NV4 User s Manual...
Page 390: ...5 Part Library Function 6 18 WindO I NV4 User s Manual...
Page 420: ...3 Text 7 30 WindO I NV4 User s Manual...
Page 628: ...2 Multi State Lamp 9 34 WindO I NV4 User s Manual...
Page 924: ...4 Meter 11 76 WindO I NV4 User s Manual...
Page 990: ...7 Timer 12 66 WindO I NV4 User s Manual...
Page 1030: ...4 Using Data and Detected Alarms 13 40 WindO I NV4 User s Manual...
Page 1098: ...4 Using the Data 15 22 WindO I NV4 User s Manual...
Page 1248: ...5 Restrictions 22 18 WindO I NV4 User s Manual...
Page 1370: ...2 Monitoring on the MICRO I 25 28 WindO I NV4 User s Manual...
Page 1388: ...4 Restrictions 26 18 WindO I NV4 User s Manual...
Page 1546: ...5 Module Configuration Dialog Box 30 36 WindO I NV4 User s Manual...
Page 1614: ...3 Settings 34 14 WindO I NV4 User s Manual...
Page 1726: ...5 Text Alignment A 10 WindO I NV4 User s Manual...