In theory, therefore, this will work?
http://cgi.ebay.co.uk/GPS901-RS232-GPS- ... .m63.l1177
I tried plugging a Garmin GPS V with an external antenna (that I know works) onto the RS232 port of an Intel based test RB but I failed to get any comms between RouterOS and Garmin.
I think so ...
The say that support NMEA0183, this is ok. I guess MT handle any speed on serial port (e.g. for GPS it's not locked to 4800 8 N 1). This module is locked to 9600. And you'll need to build some power inserter using one DB9 male <> DB9 female and feed the pin 7 of the GPS side only (the male connector) with +5Vdc.
I have one module here that's SiRF based too. It's nice, matchbox size.
Abt Garmin ... you know that it works ... where? On a PC with some navigation software? Garmin does not have some proprietary serial protocol? Most of the GPS software for PC I see has on config: GPS type ... ( )Garmin ... ( )NMEA. Try to run any terminal program (hyperterm etc) with this Garmin conectet do serial to see how the sentences looks like (they are text files on most GPS but Garmin I don't know) or on MT itself.
On MT with GPS connected to serial but keeping GPS routine disable (/system/gps set enable=no) you can see the same sentences from serial port. Open a new terminal (e.g. Winbox) and "sys serial-terminal serial0" and so there is ... you don't need an antenna connected to see the sentences, GPS send them all the time.
$GPGSV,2,2,08,18,53,155,53,21,35,119,54,22,73,232,5
[Q - quit connection] [B - send break]
[A - send Ctrl-A prefix] [R - autoconfigure rate]
3,29,18,042,43
$GPVTG,215.1,T,235.9,M,000.1,N,0000.1,K
$GPRMC,003252,A,2345.9112,S,04633.2272,W,000.1,215.1,220309,020.8,W*67
$GPGGA,003253,2345.9109,S,04633.2273,W,1,08,02.55,000750.7,M,-004.1,M,,
$GPZDA,003253,22,03,2009,+00,00
$GPGSV
Welcome back!
[mramos@WRAP-3G] > sys serial-terminal serial0
Regards;