speakup and serial hubs?

[Chris Gray]

This is a generic comment.  However, I would be cautious about stacking 
serial to USB converters on a USB hub.  Also, you are still going to 
have to address issues with serial to USB converters, even when attached 
to separate USB connectors on your motherboard at the very least.  The 
converters typically use high IRQs and strange port addresses.

Good luck, and I'd be curious to know how it goes if you take this 
aproach, especially for more than two serial devices.

Chris

On Thu, 6 Jan 2005, Tom 
Moore wrote:

> Date: Thu, 6 Jan 2005 19:39:13 -0500
> From: Tom Moore <tom at tomstroubleshooting.com>
> Reply-To: Speakup is a screen review system for Linux.
>     <speakup at braille.uwo.ca>
> To: Speakup is a screen review system for Linux. <speakup at braille.uwo.ca>
> Subject: Re: speakup and serial hubs?
> 
> I'd agree. Use the built on port for the synth and use the usb
> converter for all other serial devices and you should be ok.
>
> Tom
>
> On Thu, Jan
> 06, 2005 at 06:15:54PM -0600, Adam Myrow wrote:
>> There is always the USB to Serial converter option.  I just got a Keyspan
>> USA 19H converter.  It connects to a USB port, and has a short cable with a
>> 9-pin male RS-232 connector.  There is support for this contraption in
>> Linux, and from what I've read, Keyspan has been very supportive  of Linux.
>> I can successfully use Brltty to talk to a PowerBraille 80 via this device
>> once I re-built the kernel to support it.  It showed up as /dev/ttyUSB0.  I
>> have my doubts about it working with Speakup as a hardware synthesizer, but
>> I'd bet it would work with a Modem, or UPS.  They also make multi-port
>> versions.
>>
>>
>> -----Original Message-----
>> From: speakup-bounces at braille.uwo.ca [mailto:speakup-bounces at braille.uwo.ca]
>> On Behalf Of Justin Ekis
>> Sent: Thursday, January 06, 2005 5:27 PM
>> To: Speakup is a screen review system for Linux.
>> Subject: Re: speakup and serial hubs?
>>
>> Hi all:
>>
>> What  I was hoping for was an external box which could do this trick, but I
>> see that's not realistic at all. I thought I remembered the computers at
>> school having a box that connected to the port and gave you four serial
>> ports. Thinking about it more carefully I now remember it was only a switch
>> box and only one at a time would work.
>>
>> Really bad question, guess I'm out of luck. I don't know that I have any
>> free slots available for a card either and wouldn't feel comfortable
>> installing one if I did.
>>
>> This isn't even related to Linux now so respond off list if you like. Is
>> this something that I could go into a computer shop and have upgraded? Would
>> I perhaps have to get a new motherboard installed or something drastic like
>> that and how much would it cost?
>>
>> Justin
>> On Thu, Jan 06, 2005 at 02:47:30PM -0800, Chris Gray wrote:
>>> Hi Justin:
>>>
>>> Due to the nature of the RS232-C serial specification, there are
>>> complications about having something put together like a serial hubb.
>>> The serial hardware alone takes a fair amount of electronics, the way
>>> way serial ports are implemented through the motherboard doesn't lend
>>> itself to a hubb like you see today with USB devices.  It's a creative
>>> question though.
>>>
>>> Before USB, there were lots of board made that attempted to do what you
>>> are suggesting, or variants of that.  Enough serial devices still exist
>>> that you might be able to find such a device today.  Typically, these
>>> were boards that had 4, or more separate serial ports on them, with a
>>> ton of jumpers to modify IRQ and port addresses.  Beware of cards with
>>> connectors that are just nullcross-overs for the same port; those won't
>>> help you.  You must have separate, discrete ports and
>>> connectors/jumpers to them.
>>>
>>> whether you can find such a card that's both PCI and affordable is an
>>> interesting question. I called a local, relatively large computer store
>>> here in San Francisco Central Computers, because all this made me
>>> curious and they have fairly decent customer service.
>>> I'm slightly surprised, but It turns out they have a high speed i/o
>>> card with two ports for $19.99 from Vitex, it's even in stock!  If they
>>> carry it, I bet you could order something from Comp USA if you've got
>>> the patience, or find something localy or online.
>>>
>>> Hope this helps.
>>>
>>> Chris
>>
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-- 

Chris Gray, Sr. Technical Writer        Symantec Corporation
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