Garmin GTR 225 Installation Manual page 87

B.2.4.1.9 Set Standby NAV Frequency
This message is used to set the standby NAV
Message format:
"V" ..........................Message class. This is a GNC NAV message.
"28".........................Message identifier.
mk ...........................Standby VOR/LOC frequency:
m = desired frequency in MHz in hexadecimal, where m = desired frequency - 30h, with desired
k = desired frequency in kHz, where k = (desired frequency / 25 kHz) + 30h, with desired
"0" ...........................Reserved, data in this field will be ignored.
Example message:
This example command would set the standby VOR frequency to 111.800MHz. This is interpreted by
noting that the ASCII "?" corresponds with 3Fh, +30h = 6Fh, converted to decimal equals 111 for the MHz
portion. The kHz portion converts ASCII "P" to 50h, -30h yields 20h, x 25 kHz steps = 800 kHz.
NOTE
The GNC will check input frequencies for validity. An RS-232 serial error message output
will be generated if the frequency is invalid.
190-01182-02
Rev. F
frequency in range of 108 to 117MHz.
frequency in range of 000 to 975 kHz in 50 kHz steps, or the even numbers
from 30h to 56h.
$PGRMV28?P0<chksm><CR><LF>
GTR 225/GNC 255 TSO Installation Manual
Page B-11