Is it possible to use python to get True Full Duplex on a Serial port?
John Nagle
nagle at animats.com
Sun Aug 16 02:20:34 EDT 2009
Hendrik van Rooyen wrote:
> On Saturday 15 August 2009 14:40:35 Michael Ströder wrote:
>> Hendrik van Rooyen wrote:
>>> In the past, on this group, I have made statements that said that on
>>> Linux, the serial port handling somehow does not allow transmitting and
>>> receiving at the same time, and nobody contradicted me.
Absolutely false.
>> Despite all the good comments here by other skilled people I'd recommend to
>> determine whether the transmission line to the devices accessed support
>> full duplex.
All standard PC serial ports are full-duplex devices.
Here's a program I wrote which uses "pyserial" to drive Baudot teletypes
as full-duplex devices.
https://sourceforge.net/projects/baudotrss/
This uses an input thread and an output thread. It reads RSS feeds and
prints them on antique Teletype machines. (Reuters RSS feeds produce
a classic news ticker. Twitter RSS feeds work but look silly when
hammered out on yellow paper at 45.45 baud.)
>
> You raise a good point, that is probably not well known amongst the youngsters
> here, as simple serial multidropping has gone out of fashion.
Actually, no. Dynamixel servos as used on the latest Bioloid robots
are multidrop serial RS-485. But outside the embedded world, nobody uses
that stuff any more. (Embedded is going Ethernet; it's overkill but
works fine and is now cheap.)
John Nagle
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