[geeks] Suggestions for USB to serial adapter?

[Nadine Miller]

On Sep 5, 2009, at 12:06 AM, Jochen Kunz wrote:

> On Fri, 4 Sep 2009 16:55:39 -0700
> Nadine Miller <velociraptor at gmail.com> wrote:
>
>> It works decently, though sometimes, unplugging it will
>> send a break to the Suns.
> Unpluging what side?
>
> If you unplug the USB first and then the RS232 side it is no surprise
> to me that they sometimes send a break. If you unplug the USB side the
> power supply for the USB-to-RS232 chip goes away. When the voltage
> drops below the minimum supply voltage of the chip all strange and
> undefined things can go on inside the USB-to-RS232 chip...
>
> Then you have the problem of an unpowered RS232 transmitter connected
> to an alive RS232 receiver. This may result in undefined signal
> levels...

I'm fairly certain that I always unplugged from the Sun first before  
unplugging the USB.  I use the same precaution when using DB9->RJ45 on  
a Windows PC.  And only ever remove after closing the minicom/ 
hyperterminal session.  On Windows/Linux I am also careful to remove  
the serial connection before shutting down the OS.

As I said, I've not been able to identify what causes this behavior  
with the adaptor; it's inconsistent.  Fortunately we were able to  
finally get the crappy Avocent Cyclades working with the Suns that  
have no service processor, so it became a non-issue.  I never  
attempted using the USB serial adaptor on my Dell laptop running Linux  
to see if it was a Mac issue, since the Dell has a DB9 on it.

=Nadine=