Echelon LonTal Stack - Manual (Page 130)

118 Developing a LonTalk Stack Device Application
To process notification of a network variable update, modify the
LonNvUpdateOccurred() event handler function (in the FtxlHandlers.c file)
to call the appropriate functions in your application. The API calls this function
with the index of the updated network variable. The following figure shows the
control flow for receiving a network variable update.
LonEventPump()
LonNvUpdateOccurred()
Host Processor
Application
LonTalk Protocol Stack
and API
Receive Network
Variable Update from
Network
Add “Update Received”
Event to Queue
nviCount
Update
Configuration network variables are used much in the same way as input
network variables, with the exception that the values must be kept in persistent
storage, and the application does not always respond to changes immediately.
Example 1, below, shows the processing flow for regular network variable
updates, and example 2 shows the same flow but with the addition of a
configuration network variable.
Example 1:
This example uses the same power converter model file from the example in the
previous section, Sending a Network Variable Update. That example
demonstrated how to read the network variable inputs asynchronously by
reading the latest values from the network variables declared in the FtxlDev.c
file.
This example extends the previous example and shows how your application can
be notified of an update to either network variable. To receive notification of a
network variable update, modify the LonNvUpdateOccurred() callback
function.
In FtxlHandlers.c: