PL2303 & gui serial status display for /dev/ttyUSB(x)?

[Les]

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