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Ben Lindner wrote:
<blockquote cite="mid:4931A9A8.1000300@activ8.net.au" type="cite">Hi
All,<br>
<br>
I have just got a usb-serial cable working under XP that has been
sitting around for many years and has never worked under XP before so
did some searching for drivers and found some and it now works 100%. I
have tested it with a GPS, all good.<br>
<br>
<i>My question is, has anyone used such a cable ( USB-SERIAL ) with a
TNC without any problems. </i>I would be interested to hear any
thoughts or suggestions<br>
<br>
</blockquote>
<br>
Again, these devices vary wildly in how faithfully they emulate a real
serial port. <br>
<br>
It can depend on:<br>
<br>
1) The version of Windows you are using. [2K - XP - Vista USB
support in earlier versions of Windows is so inexorable it's not even
worth the bother in my opinion.]<br>
<br>
2) The patch level of the version of Windows you are using.<br>
<br>
3) The application you are using. [Does it care about serial port
handshaking lines (RTS, CTS, DSR, DTR, etc) being asserted correctly or
does it just ignore them? Does the app use the serial interface in
unconventional ways (such as wiggling the handshake lines for PTT, CW
keying, etc independently of the data flow on the actual TXD and RXD
data lines)? Or does it expect the port to operate at non-standard
word lengths (such as 5-bit Baudot RTTY) or odd (by today's standards)
baud rates such as 110 (ASCII RTTY) or 45 (Baudot RTTY) ? ]<br>
<br>
4) The device on the other end of the cable. [Does it have a full
multi-conductor handshaking interface that requires correct assertion
of the lines, or just a simple three-wire TXD/RXD/COMMON serial
hookup? <br>
<br>
<br>
For example, the Kenwood TH-D7 has a simple three-wire inteface while
the D700 has a full 9-pin serial port interface that can respond to
handshaking. The Kenwood radio memory programming utiltiy for the
D700 gets hung by wrong handshakes, while UIview ignores them on the
same connection to the same radio.]<br>
<br>
5) The version level of the driver for the particular chip in the
USB<-->serial cable you are using. These converter cables are
actually active devices with a dedicated controller chip, dependent on
software drivers, molded inside the DB9 housing -- they are not just a
DB9 socket at the end of a wire. <br>
<br>
[Newest is not always the greatest! I have found that the latest
drivers for the Prolific Tech chip set widely used in USB-interfaced
GPS devices and some USB-to-serial cables works perfectly on one laptop
and totally locks up another. These are different machines, but
running the same patch level of a clean install of Windows XP SP3. I
actually had to "down-grade the Prolific drivers two versions to get
Prolific-based devices to work reliably on the one machine. The
difference may lie in the particular USB root chipset INSIDE the the
computer, that the drivers have to interact with to reach the
controller in the cable.] <br>
<br>
Over time and hundreds of posts on ham-related mailing lists, the
USB<-->serial conversion products with consistently the most
favorable comments, the most stable & bug-free drivers, and
virtually no complaints are the ones made by Edgeport. <br>
<br>
That being said, I *AM* using two generic unbranded cables based on
the FDTI chipset in my APRS webserver to connect a KAM dual-port TNC
and a KPC3+. They have been cranking away for years now with no
problems at all. [I have found devices based on the FDTI chipset in
general to be less problematic than those based on Prolific Tech
chipsets. The key is to ignore any drivers included on a CD-ROM with
the device, and instead download the latest versions from the FDTI
website. [Frequently, the Taiwanese and Chinese mfrs of these devices
just include a copy of the drivers that came on a developer's CD years
ago -- often alpha or beta versions of the drivers!]<br>
<br>
<br>
<br>
<br>
<br>
<br>
--<br>
<br>
Stephen H. Smith wa8lmf (at) aol.com <br>
EchoLink Node: 14400 [Think bottom of the 2M band]<br>
Home Page: <a class="moz-txt-link-freetext" href="http://wa8lmf.com">http://wa8lmf.com</a> --OR-- <a class="moz-txt-link-freetext" href="http://wa8lmf.net">http://wa8lmf.net</a><br>
<br>
World Digipeater Map<br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/APRSmaps">http://wa8lmf.net/APRSmaps</a><br>
<br>
JavAPRS Filter Port 14580 Guide <br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/aprs/JAVaprsFilters.htm">http://wa8lmf.net/aprs/JAVaprsFilters.htm</a><br>
<br>
"APRS 101" Explanation of APRS Path Selection & Digipeating <br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/DigiPaths">http://wa8lmf.net/DigiPaths</a> <br>
<br>
Updated "Rev H" APRS <a class="moz-txt-link-freetext" href="http://wa8lmf.net/aprs">http://wa8lmf.net/aprs</a><br>
Symbols Set for UI-View, <br>
UIpoint and APRSplus:<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
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