Echelon LNS DDE Server - Manual (Page 97)

Note: To receive a response, you must establish an automatic link on resp_in in the
DDE Client before sending the request on msg_out (i.e. the response message must be
automatically forwarded to the client). Otherwise, the response will be discarded.
Specifying a Message Completion Event
Completion events are used to determine the success or failure of outgoing messages
sent by the LNS DDE Server. Completion events are not generated for messages sent
using unacknowledged or repeated service. Completion events are generated for
messages using the acknowledged or request/response service.
If the original message was sent to a single device using the acknowledged or
request/response service, the message is considered a success if an acknowledgement
or response is received from the device.
If the original message was sent to multiple devices and used acknowledged or
request/response service, the message is considered a success if acknowledgements or
responses are received from all of the destination devices. The acknowledged and
request/response services are only supported when sending messages to 64 devices or
fewer. If one or more acknowledgements or responses are not received within the
configured number of retries and timeout interval, the message is considered to have
failed. No information as to the identity of the non-responders is returned in a failure
completion event.
Use the MT topic to receive completion events. Within the MT topic, the LNS DDE
Server uses the following item format for completion events:
[device_name.]msg_complete[.msg_code] [parameters]
Where each component of the item format has the following meaning:
device_name
Optional. Specifies the name of an application device, as
defined in the LNS database. If not specified, the item
specifies all completion events.
msg_complete Required. msg_complete is a keyword, not a user-defined
name. This keyword is case insensitive.
msg_code Optional. Specifies the completion status of outgoing
messages sent with the given message code in decimal.
Parameters Optional.
LNS DDE Server User's Guide 7-5