Is it possible to use python to get True Full Duplex on a Serial port?

Hendrik van Rooyen hendrik at
Fri Aug 14 15:38:15 CEST 2009

On Friday 14 August 2009 12:54:32 Diez B. Roggisch wrote:

> How about using pyserial? With that, I never had any problems accessing
> the the serial ports, and AFAIK no duplex-problems as well. And I
> seriously doubt that these are a python-related problem - python only
> has a very thin, direct layer above the posix-calls, and doesn't do
> anything that would explain your observed behavior. The GIL is not the
> issue here either - it won't interfer with blocking IO.

I will have a look at pyserial - have never used it before.

I agree that it is probably not a Python issue, and that the GIL is 
irelevant  - I was hoping that someone had already travelled the road and 
could give me a signpost.

In the meantime I have had another idea which I have also not tried yet, 
namely to do independent opens for reading and writing, to give me two file 
instances instead of one, and to try with that.  I have no idea if it would 
make any difference, or even work at all.

My normal stuff works, but I do not like it as it is essentially busy looping 
with short sleeps in between. In the eBox, it uses most of the processor just 
to move a few bytes of I/O in and out between the serial port and the TCP/IP,
and struggles to do that better than five times a second, while the message 
time on the 115200 baud port is only about 2 milliseconds.

- Hendrik

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