Echelon LNS - Manual (Page 119)

LNS Programmer's Guide 105
• A device interface file may include information that is not included in the device
itself, such as network variable names.
• A device interface file can be used even when the device cannot be accessed by
the network engineering tool, such as during the definition phase of an
engineered mode installation.
• Importing from a device interface file may be substantially faster than recovering
interface information from a device.
• Importing from a device interface file allows LNS to accurately set the default
values for network variable characteristics such as message service type and
priority. If you recover the interface from the device, LNS will use the current
values in the first device with that program as the defaults.
• Importing from a device interface file ensures that configuration property
definitions and default values for the device are available to LNS. After
recovering an interface from a device, it is necessary to upload the configuration
definitions from the device, after the device has been commissioned and the
device application is running. Default values can be set to the current values in
the device.
The primary device interface file type is a text file with a .XIF extension. Some platforms
convert this file to alternate formats for performance optimization. For example, LNS
uses a binary device interface file (.XFB extension), and a device interface object file
(.XFO extension). Both of these files are created from the data contained within the text
device interface file. The device interface files (.XIF and .XFB file extensions) are
supplied by the device manufacturer. The optimized interface file (.XFO extension) is
automatically created and maintained by LNS when the device interface files are
imported. Note that some manufacturers supply the .XFO file with the device, which
allows for more efficient importation of the device interface.
When you add a device to an LNS network database, you must create a
DeviceTemplate object within the database to represent the device’s interface. You can
create the DeviceTemplate object by querying the desired device’s external interface
over the L ON W ORKS network, or by reading the device interface files. To read a device
interface file into a DeviceTemplate object, follow these steps:
1. Initialize the LNS Object Server and open the network and system you plan to install
your devices on. These tasks are described in Chapter 4, Programming an LNS
Application.
2. Access the System object’s DeviceTemplates collection. You can access the
DeviceTemplates collection through the System object’s TemplateLibrary object.
Dim MyTemplateLibrary as LcaTemplateLibrary
Dim MyDeviceTemplates as LcaDeviceTemplates
Set MyTemplateLibrary = MySystem.TemplateLibrary
Set MyDeviceTemplates = MyTemplateLibrary.DeviceTemplates
3. Call the DeviceTemplates collection’s Add() method to create a new
DeviceTemplate object. The programType parameter you supply to the Add
method must be set to lcaProgramTypeXif.
Dim MyTemplate as LcaDeviceTemplate
Set MyTemplate = MyDeviceTemplates.Add (“T1”, lcaProgramTypeXif)