Echelon LNS - Manual (Page 244)

LNS Programmer's Guide 230
3. Call the Advise() method on the network variable monitor point you
want to monitor. Specify the COM object created in step 1 as the object
element. At this point, LNS will stop generating the
OnNvMonitorPointErrorEvent and OnNvMonitorPointUpdateEvent
events for the monitor point, and the object specified as the object
element will start receiving UpdateErrorEvent and UpdateEvent
events for the monitor point. The Advise() method must be called from
the thread that is managing the OnNvMonitorPointErrorEvent and
OnNvMonitorPointUpdateEvent events.
NOTE: The OnNvMonitorPointEvent event will be fired by the LNS
Object Server for each network variable monitor point contained in a
monitor set when the motor set is opened to signal that the network
variable monitor point is available for use. Similarly, the
OnNvMonitorPointEvent event will be fired each time a network
variable monitor point is created in a monitor set that is currently open,
acknowledging that the network variable monitor point has been
instantiated. You should wait until this event has been fired to retrieve
an NvMonitorPoint object and call the Advise() method on it.
4. Each time the UpdateErrorEvent or UpdateEvent events are
received, the UpdateErrorEvent() or UpdateEvent() methods will be
called.
5. You can call the Unadvise() method on the network variable monitor
point at any time to return to the default behavior, where events are
invoked in the client thread.
System Management Mode Considerations
The system management mode is stored in the
MgmtMode
property of the
System
object.
This determines whether device configuration changes are propagated to the devices
(lcaMgmtModePropagateConfigUpdates), or saved for later processing
(lcaMgmtModeDeferConfigUpdates).
You should be aware of the effects that the system management mode has on monitor
and control operations. Changing the database while the system management mode is
set to
lcaMgmtModeDeferConfigUpdates
mode affects monitoring operations in
different ways. This depends on whether you are using permanent
MonitorSet
objects,
or temporary
MonitorSet
objects, and whether you are using bound or unbound monitor
and control strategies.
Temporary monitor sets use the LNS database to determine how to monitor a device.
Therefore, use of temporary monitor sets while the physical configuration of the network
differs from configuration stored in the LNS database is discouraged, since these
inconsistencies may lead to monitoring failures, or even invalid data. As a result,
Echelon recommends that you do not use temporary monitor sets while the system
management mode is set to lcaMgmtModeDeferConfigUpdates.
Permanent monitor sets use configuration data in devices that is updated only when the
management mode is
lcaMgmtModePropagateConfigUpdates
. This means that any
monitor sets and points created prior to setting the management mode to
lcaMgmtModeDeferConfigUpdates
will contain configuration data that is consistent