Garmin MX20 Installation Manual - Enabled Only)

I/O Specifications 

A-2 

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  (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