Echelon LNS - Manual (Page 89)

LNS Programmer's Guide 75
device’s network address consists of three components — the device’s
domain, the device’s subnet, and the device’s subnet ID. The LNS Object
Server is responsible for assigning each device a unique network address
when the device is installed.
• Define the information that devices share with one another. Devices
communicate with one another using high-level objects called network
variables, or low-level messages. Interoperable network devices send
messages using implicit addressing for network variable updates and
application messages. When using implicit addressing, the Neuron Chip
firmware on the application device builds and sends network variable and
application messages using information contained in tables in its
EEPROM. In order to send application messages in this fashion, the
device application specifies a message tag when sending the message.
The message tag is associated with an address table entry stored in the
device’s EEPROM.
When an LNS application requests that a device share information with
another device, an address table entry is allocated and configured on the
device sending the information. This address table entry associates the
output defined by the device application (either a network variable or a
message tag) with the domain/subnet/node address, group address or
broadcast address of the device or devices receiving the information. The
process of creating and configuring these tables is called binding or
connecting. The addressing established during this process is called a
connection. The LNS Object Server is responsible for allocating the
network resources used by connections.
• Set site-specific parameters. L ON W ORKS technology provides the
flexibility to customize and tune network behavior and response
characteristics, if required by the system. For example, network
performance can be fine-tuned by assigning devices to priority slots on a
channel. You can assign these priority slots with LNS. You can use LNS
to further customize devices by setting application-specific information
such as location, temperature set points, and calibration tables.
Installation Scenarios
The first step in writing an LNS application to install a L ON W ORKS network is to select
the installation scenario or scenarios that the application will support. Based on your
knowledge of the network and the capabilities of the installation personnel, you must
decide what steps the installer will go through to add devices and build connections, how
much flexibility will be required, and what tasks can be automated by your LNS
application. Once you choose an installation scenario, you can map the scenario to the
required objects in the LNS database, and add intelligence to the application to automate
tasks as appropriate.
The installation scenario you use to install your network determines the "look and feel"
of the network as viewed by the person responsible for network installation. The best
scenario for any given network depends on many factors, including the skill level of the
installer, the amount of flexibility desired, and the requirements of the end-user. In all
cases, the installation process should be automated as much as possible. Automation
both simplifies and speeds network installation.
The three installation scenarios are automatic installation, engineered mode installation,
and ad hoc installation. Note that you can install a network using a mix of these