Echelon OpenLNS Commissioning Tool - Manual (Page 251)

OpenLNS CT User’s Guide 235
• Any address table entries that are not associated with a network variable or message tag (source or
target) are marked as empty. A lost source or a lost target may create this scenario. Group use
counts are updated as necessary, and group IDs are freed as necessary.
• When recovering a network, OpenLNS CT cannot determine which network variables are hubs
and which ones are targets. These relationships are arbitrarily assigned.
• Because the hub and target relationships may change, the recovery may not accurately restore all
connection descriptions. If the recovery is unable to determine the correct connection description
for a connection, it uses the default connection description.
Resynchronizing an OpenLNS CT Network
You can resynchronize an OpenLNS CT drawing and the physical devices in a network with the
OpenLNS network database. OpenLNS CT keeps an OpenLNS CT drawing and its network database
synchronized by tracking and processing OpenLNS events. In the case where multiple OpenLNS CT
users are simultaneously accessing the same network database, it uses an event log that keeps all
copies of the OpenLNS CT drawing synchronized with the OpenLNS network database and with each
other.
An OpenLNS CT drawing and its network database, though, can lose synchronization due to a
hardware or software failure. When OpenLNS CT detects that an OpenLNS CT drawing and its
network database have lost synchronization or that an inconsistency exists in the drawing, it will
automatically try to resynchronize the OpenLNS CT drawing to the network database. This
resynchronization will be transparent, except that you may notice a slightly lower response time during
the resynchronization.
However, the automatic resynchronization may fail or other scenarios may occur in which you need to
manually resynchronize the network. For example, some types of changes to the OpenLNS network
database by an OpenLNS application other than OpenLNS CT, an improperly saved drawing, or
deleted entries in the OpenLNS CT event log can cause an OpenLNS CT drawing to lose
synchronization with its OpenLNS network database. You may also need to manually resynchronize
physical devices with the OpenLNS network database (to recommission all the devices on the network,
for example).
The following sections describe how OpenLNS CT automatically keeps an OpenLNS CT drawing
synchronized with its network database when one or more users are making changes to the drawing
and how to manually resynchronize the physical network, network database, and the OpenLNS CT
drawing when automatic resynchronization fails.
Automatic OpenLNS CT Drawing Synchronization
You can make changes to an OpenLNS CT drawing at the same time that another user is modifying the
network, even if the other user is modifying the same drawing page as you. OpenLNS CT uses
OpenLNS events and the OpenLNS CT event log described in the following sections to keep the
OpenLNS CT drawings synchronized with the OpenLNS network database and with each other. The
OpenLNS CT drawings will remain synchronized even as multiple users and applications access and
modify the drawings and the network database.
The OpenLNS events and OpenLNS CT event log events enable multiple OpenLNS CT users to stay
synchronized, even if they are not operating at the same time. For example, if two users start working
on a network and one of the users shuts down their computer to move to another location while the
other user continues to work, the first user’s OpenLNS CT will automatically pick up all changes
created by the other user once the first OpenLNS CT is restarted—even if the other user is no longer
using OpenLNS CT.
While it is possible for multiple users to be modifying the same page of an OpenLNS CT drawing at
the same time, if the users are working in the same subsystem, it is possible for one user to delete an