Garmin SL40 - Appendix E - Serial Interface Specifications; RS-232 Inputs; Set Active Frequency

S
er
ia
I Da tct
Spec i
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I io ns
AppnxDrx
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-
SEruer ITTERFAcE
SpEcrFrcATroNS
This appendix
inclLrdes the interface
specifications
for the RS-232 serial
port.
The
RS-232
port
can be used to
input
active and standby frequencies, and
is
used to input
frequencies from
a
remote
source. such as the SL50 and 2001GPS.
The interface
format confbtms
to NMEA
0
I
83 message
lbrrnat
specifi
cations.
The format
of
the RS-232
serial
port
is
as
follows:
Baud ratc
....... 9600
Data bits ........ 8
Stop bits.... .......................
I
Parity .............
none
Thc data
fbrrnat
is as follows:
$
PM
RRC<msg_id><nrsg_data><chksunr><cD'
The checksum is cornputed
by
arr
8
bit
addition of
thc msg id
and msg_data clraractcrs.
ignorinu carry
if
any.
Thc resulting
8
bit checksum
is
converted to two ascii characters
by
taking the uppcr
and lower nibblcs,
adding 30h
tcl
each,
and
placing
the
most
significant
character
first in
thc data rncssage.
RS-232 lxpurs
Snr
AcrrvE FREeUENCY
Message
F-ormat
$
PM R RC00mka<chksllnr><cr>
00....... rlcssagc id
mk...... activc
fiequency:
nr
-
dcsirecl frcquency
in
Mt-lz
in lrexadccinral,
whcre
nr
:
desired
fiequency
-
30h,
with desircd
ficquency
in rangc
of ll8 to 136 MIlz, or 162 Mtlz.
k
-
desired
fiequency
in kHz wherc k
-
(dcsired
ttequcncy
I
25 kHz.)
+
30h,
with
desircd
frcquency
in
rangc
of
000 to975 kHz in
25kHz
steps, or0 to 39.
a ......... trarrsccivcr
Iunction:
N
:
nornral
reccivc
opcration
M
:
enable monitor function
0
-
no
change
Example Message
$PMRRC00G4N29--cr>
Set the irctivc fiequency
to
1 I
9.l00MHz,
normal re ceive
modc.
"G"
-
I l9d
-
30h
-
71h
-
30h:47h.or an
ascii
"Gr'' "4":
100 kHzlZ5kHz+ 30h:4+
30h:34h,
oran
ascii
"4."
SL40 I nstul lutiLtn
ll Iunuul
27