pySerial: write in a blocking mode

[Peter Hansen]

Alejandro wrote:
> Peter Hansen wrote:
> 
>>Alejandro wrote:
>>
>>>I'm using pySerial to talk to a RS232 to RS485 converter. In order to
>>>control the converter, I need to control the DTR line to enable/disable
>>>de RS485 driver.
>>
>>This seems a little odd to me.  We've used several RS232-RS485
>>converters without needing to do that.  Maybe a more sophisticated
>>device would eliminate this need?
> 
> Yes. The device is very simple (I made it).

Perhaps a very simple change to it would make it as convenient as the 
commercial products.  I vaguely recall (not having checked for over a 
decade) that all they do is set the outgoing DTR line whenever there is 
data being transmitted by the PC, by using something like a 555 timer 
with a very short delay (effectively watching the start bit and any zero 
bits that are transmitted).  There are probably even example circuits 
based on this or better approaches available on the net.

-Peter