[ale] [Slightly OT] Prolific

David Tomaschik david at systemoverlord.com
Sun Nov 4 20:17:08 EST 2012


On Sun, Nov 4, 2012 at 4:31 PM, mike at trausch.us <mike at trausch.us> wrote:
> On 11/04/2012 07:12 PM, Sam Rakowski wrote:
>>
>> I've a PL2303 based serial cable that has worked fine for me, on the
>> off chances when I get to use it.
>
>
> Interesting.
>
> I must be sorely unlucky.  :)
>
> This one that I bought from fry's the other day doesn't work with Linux,
> doesn't work with Windows, and spams the kernel ring buffer with all sorts
> of error messages.
>
> If it were the first prolific device I ever bought, I'd assume it was
> defective.
>
> I bought a parallel cable ages ago (actually, I bought like six of them,
> from various places, because I was stupidly frustrated).  I even went with
> different brands, only to find out that they were all built around the same
> stupid Prolific chipset.  The problem with them all was the same:   Whenever
> I would send a print job to the printer, the printer would seemingly do
> nothing.  I could then try to cat things to the printer, which would simply
> hang.  By some strange turn of events, I realized that if I pressed the
> printers ON LINE button twice, to bring it offline and then back online, the
> printer would start printing the stuff I sent to it, but the first byte
> would be missing from the stream.
>
> Given the popularity of some of the brands (Belkin, for example, was one of
> them), I thought that it must surely be a bug in the Linux kernel. So, I
> tried in Windows.  Same problem.  Printer?  No, it worked with a real
> parallel port, and a parallel-port inkjet wouldn't print at all (no way to
> toggle the ONLINE pin).
>
> Greg KH, a kernel dev, has apparently been getting bad reports about
> Prolific hardware for a long time.  Anymore it seems that if someone comes
> to linux-usb to whine about it not working, he says "go get a real piece of
> hardware from FTDI".
>
> I wonder why they're such a problem.
>
> I wonder why yours actually works.
>
> And yes, I tested this cable with a Windows laptop.
>
> RING
>
> RING
>
> comes in, but nothing ever gets out... bits can check in any time they like,
> but they can never leave...
>
>
>         --- Mike

I have a PL2303-based cable that I routinely use with a router and it
works fine.  I've never even seen a cable based on FTDI that was
marketed for USB to standard serial, only ones for microcontroller
"serial".

-- 
David Tomaschik
OpenPGP: 0x5DEA789B
http://systemoverlord.com
david at systemoverlord.com


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