Echelon LonTal Stack - Manual (Page 65)

LonTalk Stack Developer’s Guide 53
file. NodeBuilder software is not included with the LonTalk Stack, and
must be licensed separately. See the NodeBuilder FX User’s Guide for
details about using the NodeBuilder Code Wizard.
See Appendix C, Neuron C Syntax for the Model File, for the detailed Neuron C
syntax for each type of statement that can be included in the model file.
Defining the Device Interface
You use a model file to define the device interface for your device. The device
interface for a L ON W ORKS device consists of its:
• Functional blocks
• Network variables
• Configuration properties
A functional block is a collection of network variables and configuration
properties, which are used together to perform one task. These network
variables and configuration properties are called the functional block members.
Functional blocks are defined by functional profiles. A functional profile is used
to describe common units of functional behavior. Each functional profile defines
mandatory and optional network variables and configuration properties. Each
functional block implements an instance of a functional profile. A functional
block must implement all of the mandatory network variables and configuration
properties defined by the functional profile, and can also implement any of the
optional network variables and configuration properties defined by the functional
profile. In addition, a functional block can implement network variables and
configuration properties that are not defined by the functional profile – these are
called implementation-specific network variables and configuration properties.
The primary inputs and outputs to a functional block are provided by network
variables. A network variable is a data item that a device application expects to
get from other devices on a network (an input network variable) or expects to
make available to other devices on a network (an output network variable).
Network variables are used for operational data such as temperatures, pressures,
switch states, or actuator positions.
A configuration property is a data item that specifies the configurations for a
device (its network variables and functional blocks). Configuration properties are
used for configuration data such as set points, alarm thresholds, or calibration
factors. Configuration properties can be set by a network management tool (such
as OpenLNS Commissioning Tool or a customized plug-in created for the device),
and allow a network integrator to customize a device’s behavior.
These interface components, and the resource files used to define them, are
described in the following sections.
Defining the Interface for a LonTalk Stack Application
Within the model file, you define a simple input network variable with the
following syntax:
network input type name;