[clug] USB to serial port adapter

Alex Satrapa grail at goldweb.com.au
Sat Jul 10 04:40:19 GMT 2004

On 9 Jul 2004, at 15:55, Dale Shaw wrote:

> Can anyone recommend a USB to serial port adapter ...The
> keyspan one looks alright - anyone got one?

I have been using the Keyspan USA-19 ("USB PDA Adaptor") for as long as 
I've had my Palm V, but only under Mac OS X.

For whatever reason, I've had problems when plugging it in - it will 
randomly cause all other devices on the USB hub to reset. I think it's 
drawing too much power for a bus-powered device, but only when being 
plugged in and never after it's been running for a while (I expect 
there's some component inside that draws a too-large amount of startup 
current). This gets quite distressing when I plug the PDA adaptor into 
the second port on the iMac itself (the one that my main USB hub isn't 
plugged into), and I lose everything - keyboard, mouse, mounted CF 

I've even bought a second USB hub thinking it was my original USB hub 
that was at fault. Eventually I just got used to the idea of having to 
individually reconnect my devices when this happens. I've tried this 
adaptor under Linux too, and I got the same behaviour on that Epox 
motherboard (USB bus would reset, and I'd have to reconnect all devices 
to see them again). Under Linux the behaviour was more distressing 
because usbmgr would have a chance to run the device-disconnect 
scripts. I don't know if that's changed recently.

The worst bit is that this behaviour is not the kind you can try to 
detect in advance, unless your vendor is prepared to let you take the 
thing out of the box and plug-and-play. The advantages of 
bricks-and-mortar stores over online shopping are really becoming 
painfully obvious.

Alex Satrapa

"Everyone has 20/20 vision in hindsight" -- Old Proverb
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