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

[Gene Heskett]

On Friday 29 December 2006 02:56, Les wrote:
>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".

Thanks, I was wondering if there was a reason for the 4th pin.

>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.

Google for 'roadnav', its both a free dl, and GPL.  It will need access to 
the network when you first run it to download the maps, and around 80GB 
for all the TIGRERLine (also free) maps of the US including AK & HI.  
They download by state->county name.  The maps aren't quite up to USGS 
standards, but are usable.  My local lake is on it but some of the 
details are old, and my street is on it, but about 400 feet east of its 
real location.  I'd assume there may be similar errors and approximations 
in much of that free data though.  As to whether its safe to navigate a 
dark harbor at more than trolling speeds, you'll have to check that out.
I'd guess that retracing paths would be ok though, for that mine seems to 
have a 15-30 foot repeatability accuracy and you can see that far by 
starlight.

>Regards,
>Les H

-- 
Cheers, Gene
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