| Serial Data Specifications |
APPENDIX E - SERIAL INTERFACE SPECIFICATIONS | |
This appendix includes the interface specifications for the | |
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 | |
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.
RS-232 INPUTS
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.”
Apollo SL40 Installation Manual | 27 |