**[TRACON DISPLAY MESSAGE DEFINITION]{.underline}**

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TRACON Display Layout

+--------+--------+--------+---+--------+--------+---+--------+--------+
| CF     |        |        |   | CF     |        |   | CF     |        |
| 2      |        |        |   | 2      |        |   | Gust   |        |
| Minute |        |        |   | Minute |        |   | Speed  |        |
| Dir    |        |        |   | Speed  |        |   |        |        |
| ection |        |        |   |        |        |   |        |        |
+--------+--------+--------+---+--------+--------+---+--------+--------+
| 1^st^  | 2^nd^  | 3^rd^  |   | 1^st^  | 2^nd^  |   | 1^st^  | 2^nd^  |
|        |        |        |   |        |        |   |        |        |
| Number | Number | Number |   | Number | Number |   | Number | Number |
+--------+--------+--------+---+--------+--------+---+--------+--------+
|        |        |        |   |        |        |   |        |        |
+--------+--------+--------+---+--------+--------+---+--------+--------+

TRACON Display Message Format

  ------------------------------------------------------------------------
  Char No.    Character Description              HEX Value     ASCII
                                                               Visible on
                                                               Display
  ----------- ---------------------------------- ------------- -----------
  1           Null                               00            

  2           Carriage Return                    0D            

  3           Line Feed                          0A            

  4           Flash Character^†^                 varies\*      

  5           Blink Character^†^                 7F            

  6           Fill Character                     30            

  7           CFA 2Min Direction, 1^st^ Number   varies        varies

  8           CFA 2Min Direction, 2^nd^ Number   varies        varies

  9           CFA 2Min Direction, 3^rd^ Number   30            0

  10          CFA 2Min Speed, 1^st^ Number       varies        varies

  11          CFA 2Min Speed, 2^nd^ Number       varies        varies

  12          CF Gust Speed 1^st^ Number         varies        varies

  13          CF Gust Speed 2^nd^ Number         varies        varies
  ------------------------------------------------------------------------

Transmit Duration: 417 ms

Characteristics: 20 ma, 1200 baud, async, serial,

1 start bit, 7 data bits, 2 stop bits,

logic 1, no parity.

^†^The blink and flash characters are not used by the TRACON Display to
control the displayed characteristics of the display. The null, flash
and fill characters are used to identify where the wind data starts
within the message. The wind data consists of 7 character (character
numbers 7 through 13). Any additional characters (up to approximately 40
characters) following the defined 7 wind data numbers should be ignored.

The NULL character indicates the start of a new message and does not
occur in any of the message characters that make up the rest of the
message.

\*The flash character is defined at the bit level to be:

  ---------- ------- ------- ------- ------- ------- ------- ------- -------
  BIT        0       1       2       3       4       5       6       7

             0       1       x       x       x       x       x       1
  ---------- ------- ------- ------- ------- ------- ------- ------- -------

> where x can be either a zero or a one.

This message structure is being used to be compatible with existing
LLWAS-2 and LLWAS-NE systems. The objective is to allow Contractor
developed TRACON displays to be used with the LLWAS-2 and LLWAS-NE
systems. In the LLWAS-2 and LLWAS-NE systems, the carriage return, line
feed and blink characters may or may not occur in the message.

Any status characters and display identification characters used to
query the displays and return the status of the individual TRACON
displays should use characters that are not used in the first 13
characters of the message and are outside this message definition.

The Number Characters are the set of ten ASCII numeric

characters 0 to 9 (ASCII Character set Hexadecimal values 30 to 39).