Garmin MX20 Installation Manual - page 80

I/O Specifications 

A-2 

560-1025-09 Rev E 

MX20 Installation Manual 

A.2   Binary Nearest List Data (when Extended Data is Enabled Only) 

The nearest waypoints lists are sent one waypoint per data transmission set.  The lists are sent in the 

following order: 

  LFAC 

  VOR 

  NDB 

  INT 

  User 

There is a maximum of twenty waypoints per type.  The waypoints are a maximum of 600 nm from 

the current position.  The waypoints are order by distance from current position nearest to farthest. 

The maximum time to send all lists is 100 second. Each list is updated just prior to the first waypoint 

in the list being sent. If a list is empty a shorter record will be sent with the List Item Number set to 

0xFF.  

Table A-2.  Nearest Waypoint List Data 

Byte Format 

Description 

1 Z 

‘Z’ Item Designator 

2 sddddddd  List Item Number: Packed, unsigned binary values

s                =  1 End of list, 0 all other  

ddddddd    = 1 – 20 list waypoint index 

sddddddd   = 0xFF  List Type is EMPTY (BYTE 4 terminate Item) 

3 t 

Waypoint Type:   

t = {a (airport) || v (VOR) || n (NDB) || i (INT) || u (USER)} 

4 

Cr 

‘\r’ Item Terminator <0x0d> (ONLY IF BYTE 3 = OxFF) 

4-8 ddddd 

ASCII Waypoint Identifier 

9 

10 

11 

sddddddd 

xxmmmmmm 

xhhhhhhh 

Latitude of waypoint.  Packed, unsigned binary values for degrees, minutes 

and hundredths of minutes. 

s                 =  0 North latitude, 1 South latitude 

x                 = undefined 

ddddddd     = Latitude degrees 

mmmmmm = Latitude minutes  

hhhhhhh      = Latitude hundredths of minutes 

12 

13 

14 

15 

sxxxxxxx 

dddddddd 

xxmmmmmm 

xhhhhhhh 

Longitude of waypoint.  Packed, unsigned binary values for degrees, minutes 

and hundredths of minutes. 

s                 =  0 East longitude, 1 West longitude 

x                 = undefined 

ddddddd     = Longitude degrees 

mmmmmm = Longitude minutes  

hhhhhhh      = Longitude hundredths of minutes 

16 Cr 

‘\r’ Item Terminator <0x0d>