[time-nuts] OT : different Rx and Tx baud rate on same port

["Björn"]

Tom, Bob & James,   (will answer in one response, to save some bandwidth)

I have a GPS receiver that is hard configured at 19200baud one way, and
76800baud the other.

The most convinient would be a USB serial adapter, but ExpressCard or
PC-CARD is also ok. PCI/PCIE is better than nothing.

HW is a laptop. Preferably a modern one. But one with PCMCIA is also ok.

I have a (binary only) windows program that I need to run. Windows version
either XP or preferably win7. But I am interested in running the adapter
in linux also.

In Linux I can arrange with combining two serial ports, since I have the
source. In MSWindows I do not have that luxuary.

Have seen reference to the bb-elec stuff. The closest I found now is

    http://www.bb-elec.com/Products/Datasheets/232brc_0812DSds.pdf

which convert baud rates, but I think not in the way I wish.

I have looked but not fully digested if the advanced async/sync serial
adapters can do split baud rates.

     http://www.commtech-fastcom.com/data_sheets/sab82532.pdf

It seems there was a time in the distant past where this was more common.

   " Setting the input baud rate to zero was a mechanism to allow for
split   baud rates. Clarifications in this volume of IEEE Std
1003.1-2001 have       made it possible to determine whether split
rates are supported and to       support them without having to treat
zero as a special case."

     http://manpages.ubuntu.com/manpages/hardy/man3/cfgetispeed.3posix.html

Here is an (obsolete, but with documentation from 2009 its not ancient)
serial controller from Exar

"The Independent TX/RX Baud Rate Generator feature allows the transmitter
and receiver to operate at different baud rates."

    http://www.exar.com/connectivity/uart-and-bridging-solutions/8-bit-vlio-uarts/xr16m680

Looking at the "stty" unix command. It seems clear that split baud rates
has been supported at one time.

http://www.openbsd.org/cgi-bin/man.cgi?query=stty&sektion=1

     "ispeed number
                 Set terminal input baud rate to the number given, if
                 possible.  If the input baud rate is set to zero, the input
                 baud rate is set to the value of the output baud rate.

     ospeed number
                 Set terminal output baud rate to the number given, if
                 possible.  If the output baud rate is set to zero, modem
                 control is no longer asserted.

     speed number
                 This sets both ispeed and ospeed to number."

With this much hinting, I was hoping there was still some hardware out
there supporting split baud rates.

kind regards,

    Björn

> Björn,
>
> If you can't find a black box that does this, just use two serial ports:
> Rx from one and the Tx from the other. On the software side it means
> opening two devices, but that shouldn't be hard to handle.
>
> Note bb-elec.com used to make a cute 4-port serial concentrator that would
> allow you to configure different baud rates in/out, but I see that's no
> longer a current product.
>
> Of course you could do all this with a micro or SBC, but I assume you're
> looking for a turn-key device rather than a homebrew project.
>
> /tvb
>
> ----- Original Message -----
> From: ""Björn"" <bg at lysator.liu.se>
> To: <time-nuts at febo.com>
> Sent: Friday, December 06, 2013 4:14 PM
> Subject: [time-nuts] OT : different Rx and Tx baud rate on same port
>
>
> Hi,
>
> I am looking for current serial adapters that support split baud rates.
> That is different input and output baud rate.
>
> Grateful for suggestions!
>
> kind regards,
>
>      Björn
>
>
>
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