Garmin GTR 200 GTR 200 Installation Manual - Page 63

Appendix B Serial Interface Specifications, B.1 RS-232 Inputs, B.1.1, Set Active Frequency

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APPENDIX B SERIAL INTERFACE SPECIFICATIONS This appendix includes 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 conforms to NMEA 0183 message format specifications. The format of the RS-232 serial port is as follows: Baud rate 9600 Data bits 8 Stop bits 1 Parity none The data format is as follows: $PMRRC The checksum is computed by an 8 bit addition of the msg_id and msg_data characters, ignoring carry if any. The resulting 8 bit checksum is converted to two ascii characters by taking the upper and lower nibbles, adding 30h to each, and placing the most significant character first in the data message. B.1 RS-232 Inputs B.1.1 Set Active Frequency Message Format $PMRRC00mka 00....... message id mk...... active frequency: m = desired frequency in MHz in hexadecimal, where m = desired frequency 30h , with desired frequency in range of 118 to 136 MHz, or 162 MHz. k = desired frequency in kHz where k = (desired frequency / 25 kHz) + 30h, with desired frequency in range of 000 to 975 kHz in 25 kHz steps, or 0 to 39. a......... transceiver function: N = normal receive operation M = enable monitor function 0 = no change Example Message $PMRRC00G4N29 Set the active frequency to 119.100MHz, normal receive mode. "G" = 119d - 30h = 77h 30h = 47h, or an ascii "G"; "4" = 100 kHz/25 kHz + 30h = 4 + 30h = 34h, or an ascii "4." 190-01553-00 Rev. A GTR 200 Installation Manual Page B-1

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190-01553-00
GTR 200 Installation Manual
Rev. A
Page B-1
APPENDIX B
SERIAL INTERFACE SPECIFICATIONS
This appendix includes 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 conforms to NMEA 0183 message format specifications.
The format of the RS-232 serial port is as follows:
Baud rate
...........................................
9600
Data bits
............................................
8
Stop bits
.............................................
1
Parity
.................................................
none
The data format is as follows:
$PMRRC<msg_id><msg_data><chksum><cr>
The checksum is computed by an 8 bit addition of the msg_id and msg_data characters, ignoring carry if
any. The resulting 8 bit checksum is converted to two ascii characters by taking the upper and lower
nibbles, adding 30h to each, and placing the most significant character first in the data message.
B.1
RS-232 Inputs
B.1.1
Set Active Frequency
Message Format
$PMRRC00mka<chksum><cr>
00
.......
message id
mk
......
active frequency:
m = desired frequency in MHz in hexadecimal, where m = desired frequency -
30h , with desired frequency in range of 118 to 136 MHz, or 162 MHz.
k = desired frequency in kHz where k = (desired frequency / 25 kHz) + 30h, with
desired frequency in range of 000 to 975 kHz in 25 kHz steps, or 0 to 39.
a
.........
transceiver function:
N = normal receive operation
M = enable monitor function
0 = no change
Example Message
$PMRRC00G4N29<cr>
Set the active frequency to 119.100MHz, normal receive mode. “G” = 119d - 30h = 77h -
30h = 47h, or an ascii “G”; “4” = 100 kHz/25 kHz + 30h = 4 + 30h = 34h, or an ascii “4.”