There are inexpensive adapters, such as the ones made by Plugable. They will
generally work when you are directly addressing the RS-232 hardware.

William Sommerwerck wrote in message
...
There are inexpensive adapters, such as the ones made by Plugable. They
will
generally work when you are directly addressing the RS-232 hardware.



Or the other similar I was looking at has active chipset conversion in the
adapter, but always seems to refer to fast serial links useage, I've not
seen specifically as low as 9600.
And whether Prolific or FTDI chipsets, seems to be horses for courses, and
reading around this topic a number of people seem to end up with the wrong
horse.
If it was possible to slow down the USB then just wasted some driver
download time if no connection emerges

N_Cook wrote:
reading around this topic a number of people seem to end up with the wrong
horse.

The problem is that Prolific (Tiawan) is the second largest manufacturer
of bridge chips. Prolific writes the official Windows drivers for their
chips, which manufacturers of adapters using them provide to their customers.

The largest manufacturer of bridge chips is an unnamed (at least to us in
the west) mainland Chinese company which makes almost compatible Prolific
copies.

Prolific found this out and exploited a difference in their chips from
the copies and their drivers no longer support the copies.

So if you are using Windows XP or VISTA, you can use the official Prolific
drivers with both real Prolific chips and the copies.

If you are using Windows 7 or Windows 8, it will automaticaly use the latest
drivers which will not work with the copies. If you manually install an
older version which does work, Windows update will automatically replace
it with one that does not. You have to turn off automatic updates for that
driver to continue to use those chips.

The Linux drivers, written only with the published specs work fine with
both. I believe that is also the case with MacOs, but don't hold me to it.

The Chinese vendors of cables that use the Prolific copies are now listing
them on eBay as Windows 98/ME/2000/XP, leaving off VISTA, 7 and 8.

Geoff.

--
Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379
"Owning a smartphone: Technology's equivalent to learning to play
chopsticks on the piano as a child and thinking you're a musician."
(sent to me by a friend)

N_Cook wrote:

William Sommerwerck wrote in message
...
There are inexpensive adapters, such as the ones made by Plugable. They
will
generally work when you are directly addressing the RS-232 hardware.



Or the other similar I was looking at has active chipset conversion in the
adapter, but always seems to refer to fast serial links useage, I've not
seen specifically as low as 9600.
And whether Prolific or FTDI chipsets, seems to be horses for courses, and
reading around this topic a number of people seem to end up with the wrong
horse.
If it was possible to slow down the USB then just wasted some driver
download time if no connection emerges.


USB is nothing like RS-232. The only thing they have in common is
that they are serial protocols.


Both Prolific or FTDI chipsets will do 9600 baud. I've used both at
that speed.


The Prolific 2303 goes down to 75 Baud. The driver allows you to
configure the converter like any other RS-232 port.

12000000
6000000
3000000
2457600
1228800
921600
806400
614400
460800
403200
268800
256000
230400
201600
161280
134400
128000
115200
57600
56000
38400
28800
19200
14400
9600
7200
4800
3600
1800
2400
1200
600
300
150
110
75




FTDI: http://www.ftdichip.com/Support/FTDocuments.htm

http://www.ftdichip.com/Support/Documents/TechnicalNotes/TN_107%20FTDI_Chipset_Feature_Comparison.pdf

http://www.ftdichip.com/Support/Documents/AppNotes/AN_107_AdvancedDriverOptions_AN_000073.pdf

http://www.ftdichip.com/Support/Documents/AppNotes/AN_120_Aliasing_VCP_Baud_Rates.pdf

On Tue, 9 Oct 2012 16:01:10 +0100, "N_Cook" wrote:

Or the other similar I was looking at has active chipset conversion in the
adapter, but always seems to refer to fast serial links useage, I've not
seen specifically as low as 9600.

The driver will provide you with a virtual serial port. This port's
speed (and other parameters) is configured in the same way you would a
physical serial port.

And whether Prolific or FTDI chipsets, seems to be horses for courses, and
reading around this topic a number of people seem to end up with the wrong
horse.

As Geoffrey explains, the knockoff Prolific chips are troublesome on
newer versions of Windows. If you get a genuine one, you'll be fine.
FTDI and SiLabs also work well in my experience.

If it was possible to slow down the USB then just wasted some driver
download time if no connection emerges

You don't want to slow down the USB data rate. You want to tell the
microcontroller in the converter to transmit and receive data at a
specific rate. As mentioned, you do that just as if it was a physical
serial port. The driver takes care of the rest.
--
RoRo