Echelon LonTal Stack - Manual (Page 64)

52 Creating a Model File
Model File Overview
The interoperable application interface of a L ON W ORKS device consists of its
functional blocks, network variables, configuration properties, and their
relationships. The network variables are the device’s means of sending and
receiving data using interoperable data types. The configuration properties are
the device’s means of providing externally exposed configuration data, again
using interoperable data types. The configuration data items can be read (and
typically also written) by a network tool. The device interface is organized into
functional blocks, each of which groups together a collection of network variables
and configuration properties that are used to perform one task. These network
variables and configuration properties are called the functional block members.
The model file describes the functional blocks, network variables, configuration
properties, and their relationships, that make up the interoperable interface for a
LonTalk Stack device, using the Neuron C programming language. Neuron C is
based on ANSI C, and is designed for creating a device’s interoperable interface
and implementing its algorithms to run on Neuron Chips and Echelon Smart
Transceivers. However, you do not need to be proficient in Neuron C to create a
model file for a LonTalk Stack application because the model file does not include
executable code. All tools required to process model files are included with the
LonTalk Stack; you do not need to license another Neuron C development tool to
work with a LonTalk Stack model file. The model file uses Neuron C Version 2.1
declaration syntax.
The LonTalk Interface Developer utility included with the LonTalk Stack
Developer’s Kit uses the model file to generate device interface data and device
interface files. You can use any of the following methods to create a model file:
• Manually create a model file
A model file is a text file that you can create with any text or
programming editor, including Windows Notepad. Model files have the
.nc file extension. This chapter describes the types of Neuron C
statements you can include in a model file. Appendix C describes the
syntax for the Neuron C statements.
• Reuse existing Neuron C code
You can reuse an existing Neuron C application that was originally
written for a Neuron Chip or an Echelon Smart Transceiver as a model
file. The LonTalk Interface Developer utility uses only the device
interface declarations from a Neuron C application program, and ignores
all other code. You might have to delete some code from an existing
Neuron C application program, or exclude this code using conditional
compilation, as described later in this chapter.
• Automatically generate a model file
You can use the NodeBuilder Code Wizard, included with the
NodeBuilder FX Development Tool, to automatically generate a model
file. Using the NodeBuilder Code Wizard, you can define your device
interface by dragging functional profiles and type definitions from a
graphical view of your resource catalog to a graphical view of your device
interface, and refine them using a convenient graphical user interface.
When you complete the device interface definition, click the Generate
Code and Exit button to automatically generate your model file. Use
the main file produced by the NodeBuilder Code Wizard as your model