Echelon LonMaker - Manual (Page 134)

118 Designing Networks
Reference connections are automatically used for connections between functional blocks or supernodes
in different subsystems. You can also use reference connections to simplify your LonMaker drawing
by reducing the number of crisscrossing connector shapes that can clutter a LonMaker drawing.
To use reference connection shapes, you can create new connections that are represented by reference
connection shapes (see Creating a Connection with the Network Variable Connection Dialog Box), or
you can right-click an existing connection represented by a connector shape and then click Use
Reference on the shortcut menu to change the connector shape to a reference connection shape.
Aligning Reference Connection Shapes
You can automatically align and keep aligned all the reference connection shapes in a subsystem or the
reference connection shapes attached to a specific functional block. This feature eliminates the need to
manually move functional block, connector, and connector reference shapes to keep your LonMaker
drawing organized.
To align all reference connection shapes in a subsystem, right-click an empty space in the subsystem,
point to Display Options, and then click Align All Reference Shapes on the shortcut menu. This will
set the Align Reference Shapes option on all the functional blocks in the subsystem and align all the
reference connection shapes in the subsystem based on the settings in the network properties:
Functional Block options category.
To enable automatic reference connection shape alignment for one or more functional blocks,
right-click the functional block (or select multiple functional blocks and right-click one of them), point
to Display Options, and then click Align Reference Shapes if it is not set. The reference connection
shapes attached to the selected functional block(s) will then be aligned based on the settings in the
network properties: Functional Block options category.
Once the automatic alignment feature is enabled on a functional block, all attached reference
connection shapes will follow the functional block when it is moved. In addition, reference connection
shapes will automatically be re-aligned when you make changes your LonMaker drawing (for
example, if you add or remove network variables or reference connection shapes).
When this feature is disabled, the attached reference connection shapes are no longer locked to the
location of the functional block shape. The attached reference connection shapes will initially still
move with the functional block shape, but they can also be moved independently. However, once you
move a reference connection shape, it will no longer follow the functional block shape.
See Functional Block Options in Appendix A for customizing the automatic reference connection
shape alignment feature.
Using Connection Descriptions
You can set the properties for a connection by either manually selecting a connection description or
having the LonMaker tool automatically select a connection description.
Connection Description Properties
A connection description is a set of properties, namely the message service type and addressing mode,
that apply to a network variable connection. The message service type determines how network
variable updates (messages) are delivered and verified. The addressing mode determines how a
message packet travels over the network. There are three main message service types: acknowledged,
repeated, and unacknowledged. Addressing modes include subnet/node ID for unicast connections,
and alias, broadcast, or group for multicast (fan-out) connections.
Message Service Type
You can specify one of the following message service types for each connection description. The
message service types vary in reliability and resources consumed.
• Acknowledged means that the sending device expects to receive confirmation from the receiving
device or devices that a network variable update was delivered. The sending application is