Echelon Neuron C - Manual (Page 215)

Neuron C Reference Guide 195
When an nv_update_occurs event is TRUE, the nv_in_addr variable is set to
contain the L ON W ORKS addressing information of the sending device. The type is
a structure predefined in the Neuron C language as shown below:
typedef struct {
unsigned domain : 1;
unsigned flex_domain : 1;
unsigned format : 6;
struct {
unsigned subnet;
unsigned : 1;
unsigned node : 7;
} src_addr;
struct {
unsigned group;
} dest_addr;
} nv_in_addr_t;
const nv_in_addr_t nv_in_addr;
The various fields of the network variable input address structure are:
domain Domain index of the network variable update.
flex_domain Always 0 for network variable updates.
format Addressing format used by the network variable update.
Contains one of the following values:
0 Broadcast
1 Group
2 Subnet/Node
3 Neuron ID
4 Turnaround
src_addr Source address of the network variable update. The
subnet and node fields in the src_addr are both zero (0)
for a turnaround network variable.
dest_addr Destination address of the network variable update if
group addressing is used as specified by the format field.
When the nv_in_addr variable is used in an application, its value corresponds to
the last input network variable updated in the application. The contents of
nv_in_addr are undefined if no network variable update event has occurred.
Updates occur when network variable events are checked or when post_events( )
is called (either explicitly from the program or by the scheduler between tasks)
and events arrive for network variables for which there is no corresponding event
check.
See
Monitoring Network Variables in Chapter 3, How Devices Communicate
Using Network Variables, of the Neuron C Programmer's Guide for more
description of how nv_in_addr is used.
Use of nv_in_addr enables explicit addressing for the application, and affects the
required size for input and output application buffers. See Chapter 8,
Memory
Management, of the Neuron C Programmer's Guide for more information about
allocating buffers.