Echelon LNS - Manual (Page 302)

LNS Programmer's Guide 288
Implementing an LNS Plug-In
An LNS plug-in is implemented as an ActiveX automation server. In Visual Basic, this is
done by creating a Sub Main, defining Sub Main as the startup form, and implementing
a public Application class.
Implementing an LNS Device Plug-In
Device plug-ins are a special class of plug-ins that are specific to a particular device type
(i.e. program ID). Device plug-ins provide an easy way for device manufacturers to
provide tailored software for their devices for performing configuration, monitoring, or
control functions specific to their devices.
Device plug-ins should be implemented as described in the Implementing an LNS Plug-
In section earlier in this chapter. This section provides additional guidelines you should
follow when implementing device plug-ins. You can also find more information about
device plug-ins in the LNS Plug-In Programmer’s Guide and the NodeBuilder Plug-In
Wizard documents.
Managing Device Configuration
Configuration data for a device is typically maintained by the configuration properties
stored on the device. This ensures that the device and the LNS database have a
consistent view of the device’s configuration, and allows the device to be easily replaced
when it fails. Any configuration data for the device that cannot be stored as a
configuration property within the device should be maintained as extension data, as
described in the Accessing Extension Data section earlier in this chapter. This ensures
that a plug-in can find this data, even if the user renames or moves the device or device
template within the LNS database. If the configuration data is extensive, the extension
data may consist of a key into a device specific extension database. However, Echelon
recommends the use of Extension objects, since the data stored in Extension objects is
accessible both locally and remotely.