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[aprssig] Prolific USB<>RS232 woes (Was Re: New tablet usable for APRS.)

Dave dave at g8kbv.demon.co.uk
Wed Feb 1 23:58:28 UTC 2012

While on the subject of USB<>RS232...

Does anyone have any idea what the trouble is with the recent Prolific 
drivers, on XP, Vista and 7 (32 bit.)  Myself and others have found that 
many Ham applications can have trouble now when using such chipset based 
adapters, ranging for scrambled communications, to random BSoD's.

HRD/DM780 for instance causes BSoD's at random times with my TS870, but 
DM780 on it's own works fine for hours at a time.  HRD will sometimes 
BSoD on it's own when using any of the Prolific adapters I've tried, with 
radios that have a very busy remote IO link..

A program I have to control an old Skanti radio, that uses a low speed 
byte by byte handhaked protocol, just refuses to work with the Prolific 
based adapters in any way.

However, an older FTDI based adapter works 100% with everything!  Pitty, 
it's drivers don't run on 7, and those that do, wont recognise the 'good' 
adapter.  (PID/VID issues, customised in the hardware, and of course you 
can't successfully "Hack" signed drivers any more.)

All the apps work fine too on W2k/XP etc, on hardware based "Real" COM 
port's (Antique ISA cards, and MoBo based etc.)   On one XP machine where 
I can have real COM ports, the FTDI and Prolific adapters installed, 
everything other than the Prolific hosted ports work.

We've tried altering or disabling the FIFO buffers, and so on, with 
little effect that is any better.   I've tried both sets of currently 
available drivers from Prolific's website, also those supplied with some 
of the adapters on mini CD.  All have issues.

The problem seems to be with data received from the "device" getting lost 
or scrambled between the outside world and the application.  The BSoD's 
are also worrying, buffer overflows?

Data line signal voltages and waveforms look good too, as much as you can 
tell with a 'scope that is.  (+-6V, just like the FTDI based devices.)

Any thoughts from the collective?    We've not seen any of the infamous 
"Error 10" problems, alegedly caused by "Fake" chipsets, so we're at a 
bit of a loss after several weeks trying.


Dave G0WBX.

On 31 Jan 2012 at 9:44, david vanhorn wrote:

> For what it's worth, my Acer Iconia A500 (android or windows models
> available) has a USB host port that works with the common serial port
> adaptors, plus bluetooth and wifi.

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