This module represents the BACnet Subscribe COV Property service.

The Subscribe COV Property service is used to get subscribe to changes for a particular property of an object.

Service Description (ASHRAE 135):

The SubscribeCOVProperty service is used by a COV-client to subscribe for the receipt of notifications of changes that may occur to the properties of a particular object. Any object may optionally support COV reporting. If a standard object provides COV reporting, then changes of value of subscribed-to properties of the object, in some cases based on programmable increments, trigger COV notifications to be sent to one or more subscriber clients. Typically, COV notifications are sent to supervisory programs in BACnet client devices or to operators or logging devices. The subscription establishes a connection between the change of value detection and reporting mechanism within the COVserver device and a "process" within the COV-client device. Notifications of changes are issued by the COV-server device when changes occur after the subscription has been established. The ConfirmedCOVNotification and UnconfirmedCOVNotification services are used by the COV-server device to convey change notifications. The choice of confirmed or unconfirmed service is made at the time the subscription is established. Any object, proprietary or standard, may support COV reporting for any property at the implementor's option. The SubscribeCOVProperty service differs from the SubscribeCOV service in that it allows monitoring of properties other than those listed in Table 13-1.