pySerial works in miniterm but not in my app

Dario d.corti at
Thu Oct 30 20:42:20 CET 2014

Python 2.7.6 on Mint, pySerial 2.6

I'm trying to write a console app to control a certain device via a usb com port.

In miniterm (-p /dev/ttyUSB0 -e -b 19200), I can communicate correctly with this configuration:

--- Settings: /dev/ttyUSB0  19200,8,N,1
--- RTS: inactive  DTR: inactive  BREAK: inactive
--- CTS: inactive  DSR: inactive  RI: inactive  CD: inactive
--- software flow control: inactive
--- hardware flow control: inactive
--- data escaping: raw  linefeed: CR

sw o01 + <--- I send this
sw o01 + Command OK <--- device does what it should *and* I receive this

Now my code:

import serial

s = serial.serial_for_url(
	bytesize = 8,
	parity   = 'N',
	stopbits = 1,
	rtscts   = False,
	dsrdtr   = False,
	xonxoff  = False,
	timeout  = 1 # tried without
s.close() # tried without
s.write('sw o01 +\r')
s.flush() # tried without
s.close() # tried with a sleep before close

With this I don't receive anything (tried with readline etc, omitted for readability), and the device doesn't react. Also, if I connect again with miniterm and issue the command, I first receive a "wrong command" message, as if some garbage was actually sent by my app, then it works again.

Isn't my config equivalent to the one in miniterm? Anything missing?


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