Echelon LNS - Manual (Page 139)

LNS Programmer's Guide 125
Configuring Devices
Application devices have many different types of configuration information. This data
can be roughly organized into two classes, generic configuration data and application
configuration data. This section defines these two classes of data, and describes how you
should manage each device’s configuration.
Generic Configuration Data
Some configuration data is generic to all L ON W ORKS devices. This includes information
required by the network protocol, as well as device properties that are present on all
standard application devices. The LNS Object Server reads this configuration data
automatically during installation, and exposes it through the properties of the
AppDevice object. Two examples are the Priority and Location properties.
You can use the Priority property to assign a device a specific priority slot. Set the
property to 255 to cause the LNS Object Server to assign the device the next available
priority slot. After a device’s priority slot is modified, the LNS Object Server
automatically resets the device to make the change take effect. A value of 0 indicates the
device uses a standard, non-priority communication slot, which most typical devices use.
You can use the Location property to set a device’s location field. The location field is a
6-byte field in the Neuron Chip used for storing installation-related information. To
promote language independence, text should not be stored in this field. Instead, it should
contain an index or code that can be mapped to text at the user interface. For example, in
a building control system, the floor and room number could be stored in the location field.
The AppDevice object contains a variety of other properties containing useful
information, such as the device’s program ID, authentication setting, configuration state,
and channel. When installing a device, you should set these properties, or check that
they are set to proper values. For a complete list and descriptions of the properties of the
AppDevice object, see the LNS Object Server Reference help file.
NOTE: The LonMark Interoperability Association recommends that you set the
SCPTlocation configuration property on each device to match the subsystem path of the
associated AppDevice object. This will provide optimum support for network recovery.
For more information on this, see Application-Level Recovery on page 262.
Application-specific Configuration Data
Application configuration data is defined using configuration properties. Configuration
properties can be implemented as configuration network variables or configuration
parameters. Any device can use configuration network variables. Devices that comply
with the LonMark Application Layer Interoperability Guidelines, version 3.0 or later, can
use configuration parameters. Configuration parameters are stored in files on the device,
and are accessed using the LonTalk file transfer protocol or direct memory read/write.
The LNS Object Server automatically determines and uses the best transfer option.
Configuration properties may be properties of the device, a
LonMarkObject
object, or a
network variable.
Configuration property definitions are contained in device external interface files. If a
DeviceTemplate was created using an external interface file, then configuration
property definitions are defined for the DeviceTemplate, and for every device using