Echelon OpenLDV - Manual (Page 72)

64 Sending and Receiving Messages with the OpenLDV API
For an uplink message (read from a network interface), the tag field indicates
the index into the receive transaction database for acknowledged, repeated
and request messages. When an OpenLDV application generates a response
to an uplink request message, it must save the tag value from the request,
and set the same tag value in the downlink response message.
priority
The priority field is set to indicate a message delivered with priority media
access, either uplink or downlink. When an OpenLDV application generates
a response to an uplink request message, it must save the priority attribute
from the request, and sets the response with the same priority. If the
network interface is configured without priority buffers, and a priority
request is received, the OpenLDV application sets the priority bit in the
response, but sends the response in a non-priority buffer.
path
The path field is set to 1 if the message should use the alternate path, and 0
if it should use the primary path. This feature is enabled only if the alternate
path bit is set. Alternate path is a feature of certain special-purpose mode
L ON W ORKS transceivers, such as power line (PL) transceivers.
completion code
The completion code field is set for an uplink completion event. Completion
code events are returned to the OpenLDV application for every downlink
(niCOMM) network message sent:
• The MSG_SUCCEEDS (1) value indicates that the message was
successfully delivered.
• The MSG_FAILS (2) value indicates that the message failed to be
delivered.
• Set the completion code field to MSG_NOT_COMPL (0) for
application layer buffers that are not completion events.
Messages sent to the network driver with the niNETMGMT network
interface command do not have associated completion events.
address mode
Set the address mode bit to 1 for an explicitly addressed downlink message,
and specify the network address field as a SendAddrDtl structure (see
SendAddrDtl on page 67).
Set the address mode field to 0 for an implicitly addressed downlink message,
in which case the network address field is ignored, although it must be
present. In this case, use the tag field as the index into the address table of
the Smart Transceiver or Neuron Chip in the network interface for the
destination address. For more information about the address table, see the
ISO/IEC 14908-1 protocol specification.
Set the address mode to 0 for downlink responses to uplink request messages
and network variable polls.
The address mode bit is ignored for local network management
(niNETMGMT) messages.