Garmin NavComm SL30, Installation Manual, Page: 77 / 88

Serial Interface Specifications
Apollo SL30 Installation Manual
69
“42” ............... Message identifier.
mk.................. Active COMM frequency:
m = desired frequency in MHz in hexadecimal, where m = desired
frequency - 30h, with desired frequency in range of 118 to 136MHz, or
162MHz.
k = desired frequency in kHz, where k = (desired frequency / 25kHz) +
30h, with desired frequency in range of 000 to 975kHz in 25kHz steps.
a..................... Transceiver function: N = normal, M = monitor, 0 = unchanged.
Example message:
$PMRRV42G4N<chksm><CR><LF>
This example command would set the active VOR frequency to 119.100MHz and place the
COMM radio in Normal receive mode. This is interpreted by noting that the ASCII ‘G’
corresponds with 47h, +30h = 77h, converted to decimal equals 119 for the MHz portion. The
KHz portion converts ASCII ‘4’ to 34h, -30h yields 4h, x25KHz steps = 100 kHz.
Note: The SL30 will check input frequencies for validity. An RS-232 serial error message output
will be generated if the frequency is invalid.
Note: The SL30 will ignore this message while transmitting on the active COMM frequency.
S
ET
NAV A
UDIO
M
ODE
This message is used to change the current NAV audio mode. There are three possible settings
for this mode. The first is “OFF”, which suppresses all of the NAV audio. The second is
“IDENT”, which will suppress the voice portion of the NAV audio signal and emphasize the
Morse Code station identifier. The third choice is “VOICE”, which will emphasize voice signal
and suppress the Morse Code station identifier.
Message format:
“V” ................ Message class. This is a VHF NAV message.
“31” ............... Message identifier.
a..................... NAV audio mode. “0” = OFF, “I” = IDENT, “V” = VOICE
Example message:
$PMRRV31I<chksm><CR><LF>
Set the current NAV Audio mode to IDENT.
S
ET
O
MNI
-B
EARING
S
ELECT
(OBS) V
ALUE
This message is used to set the OBS value used by the SL30 as the selected radial for computing
the course deviation from a VOR. This message will have no effect unless the SL30 is
configured to use the internal OBS source, or a serial OBS source.
Message format: