FieldServer FS-8700-73 - Manual (Page 25)

FS-8700-73 BACnet MSTP Driver Manual Page 25 of 48
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BACnet/IP or BACnet/Ethernet to BACnet/MSTP routers may not function reliably if COV functionality is
enabled as the router will make the MSTP device appear as a BACnet/IP or BACnet/Ethernet device, which
could lead the BACnet Workstation to expect unrealistic throughput performance when subscribing to
multiple points. It is recommended only to enable COV functionality on MSTP systems if the Client device
communicates directly via MSTP, or if the user knows that the throughput issue will not arise..
COV functionality (SubscribeCOV service) only applies to the Present_Value and Status_Flags properties of
BACnet Objects - the SubscribeCOVProperty service is not supported by the FieldServer. COV only works
for BACnet Map Descriptors with length set to 1. If length is not specified, then it defaults to 1, so this is
only a problem where length has been specified as greater than 1.
For analog Server Map Descriptors the user may optionally configure a COV_Increment value to adjust the
reporting threshold. If it is not set the COV_Increment defaults to zero.
COV Notifications are generated for all data objects for which a remote client has issued a SubscribeCOV-
Request. The SubscribeCOV-Request regulates whether Notifications are Confirmed or Unconfirmed. The
remote Client may also write the COV_Increment property in order to control the deadband for changes
in analog values. The COV_Increment property can be initialized via the configuration file by setting the
COV_Increment Map Descriptor Property. The value set by the configuration is an initial value that is
loaded on startup. It would be replaced by any new value written by the Client
Appendix A.7.2. Notes on Intrinsic Reporting configuration:
Intrinsic Reporting is managed by Notification Class objects. At least one Notification Class object must be
configured for Intrinsic Reporting to work.
Each Data_Object that is to be monitored by Intrinsic Reporting must be linked to a Notification Class object
via the Notification_Class Map Descriptor Property. For analog points alarm limits must be set up, and for
binary points, the Input_Alarm_State (specifying which binary value (0 or 1) to regard as the Alarm state)
must be set up.
The Notification_Class object contains properties that allow a client workstation to modify rules governing
event reporting, such as event_type, days of week, start and end times etc.
The RecipientLists are not stored permanently but are kept in volatile memory, and subscriptions must be
renewed on system restart.
A permanent static RecipientList may be configured directly on the FieldServer, eliminating the need for a
remote workstation to modify the RecipientList in order to receive Event Notifications. Using this option
makes the RecipientList read-only, i.e. it can then only be modified via the FieldServer config.csv file.
Refer to Appendix A.7.6