On Thu, 2006-12-28 at 11:14 -0500, Bob Chiodini wrote: > Gene, > > I tried a pl2303 serial to USB one and had problems. It was a radio > shack branded device. > > Using FC4 at the time it looked like only every other character was > being received by the host. Data to the device was fine. Unfortunately, > I never resolved the problem and opted for a four port Keyspan device. > No problems connecting through it to the same serial device. > > If the Garmin only has four wires, most likely the handshake is > XON/XOFF, if any. Does the Garmin "talk" correctly via one of the "real" > serial ports? > > Bob... > > Gene Heskett wrote: > > Greetings; > > > > Trying to get roadnav to talk to my elderly Garmin 12, and because I'm out > > of serial ports, the garmin 4 pin to db9 connector cable is plugged into > > the db9 end of a pl2303 serial to usb adaptor. The pl2303 is recognized > > and assigned to /dev/ttyUSB0 according to dmesg. > > > > I'm apparently getting zero data from the garmin and I suspect its the > > lack at least the 7 wire protocol at the garmin side of the pl2303. I > > believe it may even be just a 2 wire & ground setup as the garmin > > connector is only a round 4 pin, probably with little or no flow control > > as the garmin apparently runs at 4800 baud only. > > > > But, I'd like to ask here on this list: Has anyone ever made a pl2303 > > based adaptor actually work? > > > > The only other time I seriously tried to use this $40 gizmo was as an > > interface translator with the rs-232 pack of a vintage coco on the other > > end. At that time I was able to type back and forth using terminal > > programs on both, but a known good zmodem setup on the coco failed to > > move more than about 10 bytes of a 10k file when I had minicom attempt > > the transfer. At the time I also suspected config/handshake problems and > > eventually gave up, but now I think the pl2303 may be busted or > > miss-configured, hence the request for a gui program to monitor > > individual wire status at the db9 connector, but do it > > using /dev/ttyUSB(x). > > > > Is this latter idea even possible? > > > > Thanks everybody. > > > > > Sorry to just butt in here, but I am a sailor and use lots of GPS products. You will probably find that the garmin implements NMEA-183c, which does not use XON/XOFF, but simply ends messages with Carriage returns. You can find the commands in either the Garmin manual (if you have it), or on line at Garmin.com. They are a pretty good company in my experience. Their interface is really "three wire" with a power option. Most of their older equipment used the 4 pin round plug, with ground, +12, serial in and serial out. I don't remember the pinout, but I also have an older 12 model wired to the radar on my boat to give position and waypoints to the radar screen. It also makes a nice 2nd GPS "just in case". I am not familiar with the software you are using. Is it under GPL, or is it a commercial product? I have been looking for a reasonably cost effective software package to enable me to put a low cost nav station setup on my boat. Regards, Les H
