**IEEE P1451.3 Proposal**

+-----------------+----------------------------------------------------+
| Proposal Title: | Enhancements to Transducer Bus Management Messages |
+-----------------+----------------------------------------------------+
| Proposal        | 03-012                                             |
| Number:         |                                                    |
+-----------------+----------------------------------------------------+
| Revision        | A                                                  |
| Number:         |                                                    |
+-----------------+----------------------------------------------------+
| Date:           | 37694.38                                           |
+-----------------+----------------------------------------------------+
|                 |                                                    |
+-----------------+----------------------------------------------------+
| Name:           | Larry Malchodi                                     |
+-----------------+----------------------------------------------------+
| Company:        | Boeing                                             |
+-----------------+----------------------------------------------------+
| Phone Number:   | 206-655-5695                                       |
+-----------------+----------------------------------------------------+
| Fax Number:     | 206-655-7724                                       |
+-----------------+----------------------------------------------------+
| Email Address:  | <larry.a.malchodi@boeing.com>                      |
+-----------------+----------------------------------------------------+
|                 |                                                    |
+-----------------+----------------------------------------------------+
| Proposal        | Initial Draft                                      |
| Status:         |                                                    |
|                 | Revised Draft                                      |
|                 |                                                    |
|                 | [X]{.underline} Ready for Vote                     |
+-----------------+----------------------------------------------------+
| Impacts:        |                                                    |
+-----------------+----------------------------------------------------+
| Action:         | [X]{.underline} Approved                           |
|                 |                                                    |
|                 | Approved with changes                              |
|                 |                                                    |
|                 | Rejected                                           |
|                 |                                                    |
|                 | Returned for revision                              |
+-----------------+----------------------------------------------------+
|                 |                                                    |
+-----------------+----------------------------------------------------+

Summary of Issue:

Alice Law pointed out that there was no description of the Disarm
Streaming message under clause 10.3.5 in draft D2.03. This description
was contained in proposal P02-025F and mistakenly removed in proposal
P02-25G. Therefore, it was not in proposal P02-25H that was approved by
the working group. In addition, the current description in that section
should be enhanced to point the reader to those services that add
constraints or specify behavior of the messages.

Discussion:

Proposed solution:

Draft changes:

### 10.3.5 Transducer bus management messages

The transducer bus management message shall be as listed in Table 1. All
of these messages are sent using the short format as described in
10.3.3.

Table 1---Transducer bus management messages

  ---------- ---------------------------- ----------- ------------- -------
  Message    Command                      Addressed                 
  code                                    to                        

                                          Broadcast   Specific TBIM TBC

  0          Reserved                     ---         ---           ---

  1          Initiate discovery           Yes         No            No

  2          Discovery reply              No          No            Yes

  3          Assign alias                 Yes         No            No

  4          Assign alias response        No          No            Yes

  5          Assign time slot             No          Yes           No

  6          Assign time slot reply       No          No            Yes

  7          Define epoch                 Yes         No            No

  8          Disarm streaming             Yes         No            No

  9          Beginning-of-epoch message   Yes         No            No

  10         Start asynchronous interval  Yes         No            No

  11         Reflect                      No          Yes           No

  12         Reflect reply                No          No            Yes

  13         Enable transmitter           Yes         Yes           No

  14         Disable transmitter          Yes         Yes           No

  15 -- 127  Reserved                     ---         ---           ---

  128 - 255  Open for manufacturers       ---         ---           ---
  ---------- ---------------------------- ----------- ------------- -------

#### 10.3.5.1 Initiate discovery message

A request for the InitiateDiscovery service (see 9.4) causes the Data
Link layer to issue an Initiate discovery message to all TBIMs on the
bus. The data field for this message shall be as shown in Table 2. Only
the TBC shall generate this message..

Table 2---Initiate discovery message data field

  ---------- ---------- --------------------------------------------------
  Data Field Data Type  Function

  1          U8E        This field shall contain the message code shown in
                        Table 1.
  ---------- ---------- --------------------------------------------------

#### 10.3.5.2 Discovery reply

The receipt of the request alias service request causes the service in
the TBIM Data Link layer (see 9.5) to wait for an initiate discovery
message from the TBC. Upon receipt of this message it shall return a
Discovery reply message containing the fields shown in Table 3 to the
TBC using the asynchronous communications mode. This reply shall only be
generated if the TBIM does not currently possess a TBIM Alias
assignment.

This message is required in all TBIMs.

Table 3---Discovery reply message data field

  ---------- ---------- --------------------------------------------------
  Data Field Data Type  Function

  1          U8E        This field shall contain the message code shown in
                        Table 1.

  2          UUID       This field shall contain the eighty-bit UUID for
                        the TBIM.
  ---------- ---------- --------------------------------------------------

#### 10.3.5.3 Assign alias message

A request for the AssignAlias service (see 9.4.2) causes an assign alias
message to be broadcast to all devices on the transducer bus. The data
field for this message is shown in Table 4. This message shall be
transmitted using the asynchronous transmission mode. The TBC is the
only device on the bus thatoshall generate this message. All TBIMs shall
be able to accept and respond to it. All TBIMS shall monitor for
reassignment of their alias (see 9.5.2).

Table 4---Assign alias message data field

  ---------- ---------- --------------------------------------------------
  Data Field Data Type  Function

  1          U8E        This field shall contain the message code shown in
                        Table 1.

  2          UUID       This field shall contain the eighty-bit UUID for
                        the TBIM.

  3          U8C        The eight-bit alias for the TBIM.
  ---------- ---------- --------------------------------------------------

#### 10.3.5.4 Assign alias response

Upon receipt of an assign alias message from the TBC, the TBIM shall
transmit an assign alias response message containing the information
listed in e only when they receive an assign alias message that contains
their UUID.

Table 5---Assign alias response message data field

  ---------- ---------- --------------------------------------------------
  Data Field Data Type  Function

  1          U8E        This field shall contain the message code shown in
                        Table 1.

  2          U8E        Assigned alias

  3          U8E        Asynchronous-only flag (same as in PHY TEDS)

  4          U8C        Highest supported payload encoding (same as in PHY
                        TEDS)

  5          F32        Start delay (same as in PHY TEDS)

  6          F32        Reflect delay (same as in PHY TEDS)

  7          F32        Reflect delay uncertainty (same as in PHY TEDS)
  ---------- ---------- --------------------------------------------------

#### 10.3.5.5 Assign time slot message

Upon receipt of a SetupStreamingCommunicationChannel service request the
TBC shall compute the number of packets required and the beginning time
slot for each packet from the information supplied in the request and
internally maintained information about the layout of the isochronous
interval. It shall then broadcast an assign time slot message containing
the information in Table 6 to the TBIM. Only the TBC shall generate this
message.

Table 6---Assign time slot message data field

  ---------- ---------- --------------------------------------------------
  Data Field Data Type  Function

  1          U8E        This field shall contain the message code shown in
                        Table 1.

  2          U16E       The sixteen-bit TransducerChannel Address

  3          U16C       The beginning time slot for a packet.

  4          U8C        Number of consecutive slots required
  ---------- ---------- --------------------------------------------------

#### 10.3.5.6 Assign time slot reply message

Upon receipt of an assign time slot message the TBIM shall return an
assign time slot reply message containing the information in Table 7 to
the TBIM. TBCs shall not generate this message.

Table 7---Assign time slot reply message data field

  ---------- ---------- --------------------------------------------------
  Data Field Data Type  Function

  1          U8E        This field shall contain the message code shown in
                        Table 1.

  2          U8E        The status as listed in Table 8.
  ---------- ---------- --------------------------------------------------

Table 8---Assign time slot status bits

  ----- ------------------------------------------------------------------
  Bit   Function

  0     This bit shall be set to 1 to indicate that the message was
        received and processed successfully.

  1     This bit shall be set to 1 if the TBIM does not support streaming
        data.

  2     Reserved

  3     Reserved

  4     Open to manufacturers

  5     Open to manufacturers

  6     Open to manufacturers

  7     Open to manufacturers
  ----- ------------------------------------------------------------------

#### 10.3.5.7 Define epoch message

Upon the receipt of the Initiate Streaming Communications service
request the TBC shall issue the define epoch message as defined in Table
9 to all TBIMs on the bus. This message has two arguments. These two
arguments define the length of the isochronous and the asynchronous
intervals. The maximum length of the isochronous interval is 1200 slot
times. The minimum length of the asynchronous interval is 50 slot times.
The epoch length is the sum of the isochronous interval and the
asynchronous interval and shall not exceed 1250 slot times. If the
isochronous interval length is zero then the bus is being operated in
the asynchronous mode only and the value in the asynchronous interval
argument is not used. The default condition after reset or power up is
with the length of the isochronous interval equal to zero.

TBIMs shall not generate this message.

Table 9---Arguments for the define epoch message

  ---------- ---------- --------------------------------------------------
  Data Field Data Type  Function

  1          U8E        This field shall contain the message code shown in
                        Table 1.

  2          U16C       Isochronous interval - This field contains the
                        number of slot times that are required in the
                        isochronous interval (See Error: Reference source
                        not found). The isochronous interval length
                        requires a maximum of eleven bits and they shall
                        be in the eleven least significant bits of the
                        U16C. The five most significant bits shall be
                        zero.

  3          U16C       Asynchronous interval - This field contains the
                        number of slot times that are required in the
                        asynchronous interval (See Error: Reference source
                        not found). The asynchronous interval length
                        requires a maximum of eleven bits and they shall
                        be in the eleven least significant bits of the
                        U16C. The five most significant bits shall be
                        zero.
  ---------- ---------- --------------------------------------------------

#### 10.3.5.8 Disarm streaming

A request for this service (see 9.2.4) causes the Data Link layer in the
TBC to issue a disarm streaming message to all TBIMs on the bus. The
data field for this message shall contain the information shown in Table
34. Only the TBC shall generate this message.

Table 34---Terminate streaming message data field

  ---------- ---------- --------------------------------------------------
  Data Field Data Type  Function

  1          U8E        This field shall contain the message code shown
                        inTable 1.
  ---------- ---------- --------------------------------------------------

#### 10.3.5.9 Beginning-of-epoch message

This message is always broadcast. It marks the beginning of an
isochronous transmission interval. Isochronous transmission intervals
are 0.25 seconds or less in length so if this message is not received
within a one second period TBIMs may assume that the bus is being
operated asynchronously without a defined epoch. The data field for this
message shall be as described in Table 10. This message always occupies
slot zero in the isochronous interval.

Only the TBC shall issue this message.

Table 10---Beginning-of-epoch message data field

  ---------- --------- ---------------------------------------------------
  Data Field Type      Function

  1          U8E       This field shall contain the message code shown in
                       Table 1.

  2          U16C      The epoch number to be used during the next epoch.
                       The epoch is incremented for each new epoch. It
                       rolls over to zero for the next epoch after it
                       reaches 65,535. This epoch number shall be written
                       into the sequence number register defined in Error:
                       Reference source not found at the beginning of the
                       next epoch.

  3          U8C       Number of solicited retransmissions in this message
                       = N

                       Fields 4 and 5 will be repeated N times.

  4          U16C      The slot number in which the invalid packet began
                       being transmitted.

  5          U8E       Reply priority
  ---------- --------- ---------------------------------------------------

The data link layer may need to communicate the receipt of this message
to the TBIM application. This may be done in either of two ways. By a
hardware signal or by a trigger message addressed to the TBIM using the
trigger protocol. If a message is sent using the trigger protocol, it
shall have the form described in Table 11.

Table 11---Trigger message resulting from a beginning-of-epoch message

  ------------ ---- ---- ---- ---- ---- ---- ---- --------- ---- ---- ---- ----- ---------- ---- ----
  1-Octet                                         1-Octet                                        

  1            1    1    1    1    1    0    0    0         0    0    0    0     0          0    0

  5            4    3    2    1    0    9    8    7         6    5    4    3     2          1    0

  Protocol                              0    0    Version                  ---   Priority        
  Identifier                                                                                     

  TBIM Alias                                      zero                                           

  TBIM Alias                                      zero                                           
  ------------ ---- ---- ---- ---- ---- ---- ---- --------- ---- ---- ---- ----- ---------- ---- ----

Solicited retransmissions may be sent in this message for packets
received with errors in the previous epoch. Fields 4 through 6 are used
for this function.

To avoid collisions each packet to be retransmitted shall be assigned a
different priority starting at priority seven and working down.

Note: This technique allows for the possibility of up to seven different
packets receiving a solicited retransmission message during any one
epoch. If less priority levels are used for solicited retransmissions
then fewer packets can receive a solicited retransmission request in one
epoch. The length of the asynchronous interval will also limit the
number of packets that can be retransmitted.

Note: The solicited retransmissions are from data that was sent in the
previous epoch. If these packets are not retransmitted within the
asynchronous interval of this epoch they are lost. This means that these
packets should have the highest priority with lower priorities used by
non-time critical traffic.

The TBIMs do not reply to the data link layer in the TBC to any of this
communication. A packet may be retransmitted as a result of a solicited
retransmission but that communication is directed up through the
protocol stack.

#### 10.3.5.10 Start async message

This message is always broadcast to all TBIMs on a bus. It marks the end
of an isochronous transmission interval and the beginning of the
asynchronous interval. The data field for this message is shown in Table
12. This message always occupies the last slot in the isochronous
interval. Only the TBC shall generate this message.

Table 12---Start async message data field

+---------+---------+--------------------------------------------------+
| Data    | ###     | Function                                         |
| Field   | #### Da |                                                  |
|         | ta Type |                                                  |
+---------+---------+--------------------------------------------------+
| 1       | U8E     | This field shall contain the message code shown  |
|         |         | in Table 1.                                      |
+---------+---------+--------------------------------------------------+
| 2       | S32     | This field gives time error between when the     |
|         |         | Beginning-of-epoch message should have been      |
|         |         | transmitted and when it was actually             |
|         |         | transmitted. It is a signed 32-bit two's         |
|         |         | complement integer giving the time error in      |
|         |         | nanoseconds. If the TBC does not provide this    |
|         |         | information the contents of this field shall be  |
|         |         | zero.                                            |
+---------+---------+--------------------------------------------------+

#### 10.3.5.11 Reflect message

The TBC issues a message as shown in Table 13 when it receives a request
for the delay measurement service (see 9.9). This message shall be
transmitted using the asynchronous transmission mode. Only the TBC shall
generate this message.

Table 13---Reflect message data field

  ---------- ---------- --------------------------------------------------
  Data Field Data Type  Function

  1          U8E        This field shall contain the message code shown in
                        Table 1.

  2          U8C        The eight-bit alias for the TBIM.
  ---------- ---------- --------------------------------------------------

#### 10.3.5.12 Reflect reply

The TBIM changes the message code in the first field of the reflect
request message as shown in Table 13, the source address and the
destination address and returns the message to the TBC with a consistent
delay between receipt and retransmission. This message shall be
transmitted using the asynchronous transmission mode. Only TBIMs shall
generate this message.

#### 10.3.5.13 Enable transmitter

A request for the enable transmitter service (see 9.6.2) causes an
enable transmitter message to be broadcast to all devices on the
transducer bus or to a specific TBIM. The data field for this message is
shown in Table 14. This message shall be transmitted using the
asynchronous transmission mode. Only the TBC shall generate this
message.

Table 14---Enable Transmitter message data field

  ---------- ---------- --------------------------------------------------
  Data Field Data Type  Function

  1          U8E        This field shall contain the message code shown in
                        Table 1.
  ---------- ---------- --------------------------------------------------

#### 10.3.5.14 Disable Transmitter message

A request for this service (see 9.6.1) causes a disable transmitter
message to be broadcast to all devices on the transducer bus or to a
specific TBIM. The data field for this message is shown in Table 15.
This message shall be transmitted using the asynchronous transmission
mode. Only the TBC shall generate this message.

Table 15---Disable Transmitter message data field

  ---------- ---------- --------------------------------------------------
  Data Field Data Type  Function

  1          U8E        This field shall contain the message code shown in
                        Table 1.
  ---------- ---------- --------------------------------------------------