Please clarify: QUEUED_MESSAGE (10.3 Collection of Queued and Status Messages)

[berntd]

Hello

I need clarification on section 10.3.1 please.

It states (10.3.1 3rd paragraph p46) that if there are no queued messages pending, the device will respond with a status message(s) instead.

This seems to imply the PD (Status Type Requested) gets ignored whenever there is a queued message pending.


If that is the case, then what happens if there is a queued message pending and the controller sets the PD = STATUS_GET_LAST_MESSAGE?

Does the device then respond with the queued message or the last message?
:confused:


Regards
Bernt

[ericthegeek]

STATUS_GET_LAST_MESSAGE should always return the last message that was sent.

STATUS_GET_LAST_MESSAGE is used to handle the situation where a Status or Queued message is lost or corrupt. If the controller is issuing "STATUS_GET_LAST_MESSAGE" it's because it believes the previous message was not delivered properly. Thus, the responder needs to re-send the previous message to ensure it's delivered properly. Otherwise that message could be permanently lost.