Echelon Neuron C - Manual (Page 214)

194 Built-In Variables, Objects, Symbols, and Semaphore
Example 1:
signed long switch_state;
when (io_changes(switch_in))
{
switch_state = input_value;
}
Here, the value of the network variable switch_state is set to the value of
input_value (the switch value that was read in the io_changes clause).
However, there are some I/O models, such as pulsecount, where the true type of
the input value is an unsigned long. An explicit cast should be used to convert
the value returned by input_value to an unsigned long variable in this case.
Example 2:
unsigned long last_count;
IO_7 input pulsecount count;
when (io_update_occurs(count))
{
last_count = (unsigned long)input_value;
}
msg_tag_index Variable
The msg_tag_index variable contains the message tag for the last msg_completes,
msg_succeeds, msg_fails, or resp_arrives event. When one of these events
evaluates to TRUE, msg_tag_index contains the message tag index to which the
event applies. The contents of msg_tag_index is undefined if no input message
event has been received. The type is unsigned short.
nv_array_index Variable
The nv_array_index variable contains the array index for a nv_update_occurs,
nv_update_completes, nv_update_fails, nv_update_succeeds event. When one of
these events, qualified by an unindexed network variable array name, evaluates
to TRUE, nv_array_index contains the index of the element within the array to
which the event applies. The contents of nv_array_index will be undefined if no
network variable array event has occurred. The type is unsigned int.
nv_in_addr Variable
The nv_in_addr variable contains the source address for a network variable
update. This value can be used to process inputs from a large number of devices
that fan-in to a single input on the monitoring device. When the devices being
monitored have the same type of output, a single input network variable can be
used on the monitoring device. The connection would likely include many output
devices (the sensors) and a single input device (the monitor). However, the
monitoring device in this example must be able to distinguish between the many
sensor devices. The nv_in_addr variable can be used to accomplish this.