QDP Sequence diagram.

User application                                    |<--------------------- RTI ------------------------->|
                                                    |                                                     |
+------+                                            +------+                +------+   +------+   +-------+
|      |                                            |      |                |      |   |      |   |       |
|  BC  |                                            |  PP  |                |  FP  |   |  TB  |   |  AMT  |
|      |                                            |      |                |      |   |      |   |       |
+---+--+                                            +---+--+                +---+--+   +---+--+   +---+---+
    |                                                   |                       |          |          |
    |                                                   |                       |          |         +-+
    |    send_quick_data(RS_ECHO | RS_CONF | RS_REF )  +-+                      |          |         | |
    +------------------------------------------------->| |                      |          |         | +------------+
    |                                                  | |                      |          |         | |            |
    |           user can check Transmit Buffer         | |                      |          |         | |            |
    |<-------------------------------------------------+ |                      |          |         | |            |
    |                                                  | |                      |          |         | |  fill in   |
    |           get_quick_data                         | |                      |          |         | |            |
   +-+------------------------------------------------------------------------------------>|         | | aquisition |
   | |                                                 | |                      |          |         | |            |
   | |                                                 | |                      |       acq_msg      | |  message   |
   | |                                           if (RS_ECHO | RS_CONF)         |<-------------------+ |<-----------+
   | |                                                 | |         ctrl_msg     |          |         | |
   | |                                                 | +--------------------->|          |         | |
   | |                                                 | |         conf_msg     |          |         | |
   | |                                                 | |                      |          |         | |
   | |                                                 | |                      |          |         | |
   | |                                           else (RS_REF)                  |          |         | |
   | |                                                 | +----------------+     |          |         | |
   | |                                                 | |   change RTI   |     |          |         | |
   +-+                                                 | |  configuration |     |   fill   |         | |
    |                                                  | |<---------------+     +--------->|         | |
    |                                                  | |                      |  buffer  |         | |
    |                                          POWC data is ready               |          |         | |
    |<-------------------------------------------------------------------------------------+         | |
    |                                                  | |                      |          |         | |
    |                                                  +-+                      |          |         | |
    |                                                   |                       |          |         | |
    |                                                   |                       |          |         | |
    |                                                   |                       |          |         | |
    |                                                   |                       |          |         +-+


    BC  - Bus Controller. Application level.
    PP  - Process Packet.
    FP  - Feed Packet.
    TB  - Transmit Buffer.
    AMT - Acqusition Message Task thread.