Garmin GNS 480, Installation Manual

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Appendix B - Serial Interface Specifications
GNS 480 (CNX80) Installation Manual 560-0982-01 Rev A B-13
B.2.1.4.3 Remote VOR List
The following two commands work together in allowing the GNS 480 to provide a list of VOR
frequencies to a remote device (such as the SL30). The GNS 480 will send a sequence of Remote VOR
Input commands (message identifier 20). When all of the VOR Input commands have been sent, the
GNS 480 will send a Remote VOR List Trailer command (message identifier 21) to terminate the list.
The transmitted list should not be considered complete by remote device until it receives the trailer
message. The remote device should maintain a single remote VOR list, so each list transmitted will
replace any previous list. There may be up to twenty entries in the remote VOR list.
B.2.1.4.3.1 Remote VOR Output
This output is used to provide VOR frequency data that is used for the remote recall function.
The data consists of five characters for the VOR station identifier followed by two characters defining
the VOR frequency.
Message format:
“V” Message Class. This is a VHF NAV message.
“20” Message Identifier.
vvvv VOR station identifier. Note that if the station identifier is less than four characters, then
the trailing characters will be filled with spaces. Station Identifiers are restricted to using
ASCII characters 0-9 and A-Z.
mk Frequency: m = MHz, where m = desired MHz frequency – 30h, with the desired
frequency ranging from 108 to 117, or 3Ch to 45h; k = kHz, where k = (desired kHz
offset / 25 kHz) + 30h, with desired frequency range of 000 to 950 kHz in 50 kHz steps,
or the even numbers from 30h to 56h. Note that the field will be checked to ensure that
it is in range and a valid VOR frequency. Frequencies used for localizers, which are in
the range of 108.10 to 111.95 MHz, will not be accepted in this message type.
Example message:
$PMRRV20UBG<Sp>E@<chksm><CR><LF>
VOR station identifier is “UBG ”, VOR frequency is 117.400 MHz.
B.2.1.4.3.2 Remote VOR List Trailer
This output command marks the end of a VOR list sent by the GNS 480.
Message format:
“V” Message Class. This is a VHF NAV message.
“21” Message Identifier
Example message:
$PMRRV21<chksm><CR><LF>
Indicates the start of a remote VOR list.
B.2.1.4.4 Remote Localizer List
The following two commands work together in allowing the GNS 480 to provide a list of localizer
frequencies associated with an airport to a remote device (such as the SL30). The GNS 480 will first send
the Remote Localizer List Header command (message identifier 22), followed by a sequence of Remote