Re: [python-win32] Python - connexion to serial port
Schoeni, Yann wrote: > > > I thought it would be a great idea to keep it open during the > application life time for one reason. > > > > My webserver (running on windows) got a Velleman VM8090 module plugged > in with a usb cable, my serial port is virtual. > > > > 7) Sometimes, the script return « The Serial port is already > open », and a *delay is identified*. Below the function that open the > port : > > 8) Because of this delay I was just thinking about keeping the > serial port open while the application is running. > > > > What do you guys think ? $ > There are two possible solutions. The only time the port should be open is if you are already processing another request. No matter what you do, there's always going to be a delay in that case. Your problem, then, is to serialize access to the serial port, to ensure there's only one request at a time. Your proposed solution is certainly workable. You could create a long-running "serial server" that keeps the serial port open and accepts requests from your web server. The other solution is to change your script so that IT keeps retrying until it's able to open the port, with a short delay between each attempt. That way, the web server would always see success. The delay with the two solutions should be about the same; you're always going to have to wait for request A to finish before request B starts, but the second solution would be easier, from where you are now. -- Tim Roberts, t...@probo.com Providenza & Boekelheide, Inc. ___ python-win32 mailing list python-win32@python.org https://mail.python.org/mailman/listinfo/python-win32
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Re: [python-win32] Python - connexion to serial port
Ok guys,
I'm gonna try to give you a full explanation.
I thought it would be a great idea to keep it open during the application life
time for one reason.
My webserver (running on windows) got a Velleman VM8090 module plugged in with
a usb cable, my serial port is virtual.
Working process :
1) A QR code is read by a QR code reader
2) The QR code is paste into an input field and send to a controller
3) The controller checks the validity of the code in agreement with a
database
4) If the code is approuved the controller use shell_exec to open a python
command line
5) A python script is call with args like this :
Python C:\temp\gate.py on
6) Every time the script is launch, it open the serial port, send the
command depending on the argument and close it.
7) Sometimes, the script return < The Serial port is already open >, and a
delay is identified. Below the function that open the port :
def open_device() :
try:
print("Opening serial port")
ser = serial.Serial(
port='COM200',
baudrate=19200,
parity=serial.PARITY_NONE,
stopbits=serial.STOPBITS_ONE,
bytesize=serial.EIGHTBITS,
)
except IOError:
print("Serial port already open !")
ser.close()
ser.open()
return ser
8) Because of this delay I was just thinking about keeping the serial port
open while the application is running.
What do you guys think ? $
Best wishes !
Yann Schoeni
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