Echelon FTXL - Manual (Page 214)

202 Example FTXL Applications
For more information about creating and using a model file, see Creating a Model
File on page 23.
To change the L ON W ORKS interface and functionality of the example application,
perform the following steps:
1. Define the interface in the Simple Example.nc model file.
2. Run the LonTalk Interface Developer utility to generate an updated
application framework.
3. Make appropriate changes to the callback handler functions in the
FtxlHandlers.c file or the main.c file.
4. Rebuild the project.
5. Optional: Load the generated XIF file into the FTXL Transceiver.
6. Load the new executable file into the Nios II processor.
The Dynamic Interface Example Application
The dynamic interface example application demonstrates the basics of using both
dynamic network variables and the L
ON M ARK changeable-type protocol in an
FTXL application. The example is not a complete implementation of the protocol,
but is meant to serve as a starting point for writing your own application.
To demonstrate dynamic network variables, the example application allows you
to add, modify, or delete network variables of type SNVT_amp. Each output
dynamic network variable represents the aggregated current consumption of one
or more input dynamic network variables. For this example, the output dynamic
network variables represent logical circuits. You can define as many circuits as
needed, but the total number of dynamically added network variables can be no
more than 50.
The dynamic network variables must use the following naming convention:
• For output network variables, use the name nvoAmp plus a single-
character suffix that represents a particular logical circuit.
• For input network variables, use the name nviAmp, plus the suffix for the
corresponding output network variable, with an additional suffix that
identifies the particular input. The additional suffix can be one or more
characters.
Example: For logical circuit A, you could name the output network variable
nvoAmpA, and you could name three of its input network variables nviAmpA01,
nviAmpA02, and nviAmpA03. The value of the nvoAmpA network variable
would be the aggregrate sum of the values of the three input network variables.
The example application maintains an array for a map of the circuits defined for
the device. The application uses the functions described in
Application-Specific
Utility Functions on page 213 to maintain the circuits of dynamic network
variables and to propagate them to the network.
To demonstrate changeable-type network variables, the example application has
a configuration network variable (CPNV) named nciNvType, which maintains the
current type and last-known good value of the two network variables, nviVolt and
nvoVoltFb. The application supports changing the network variable type for
these two network variable between the default type (SNVT_volt) and the