Problem to communicate with serial port

[tekaya05]

I am using ST32 connected to the computer with USB cable. this micro-controller is already programmed and should give me two values
(it has worked on windows 10 I just replaced '/dev/ttyS1' with 'COM1').
the problem is that when i compile my program it doesn't show any Errors. I don't even know if I am communicating with the right port or not.

DO you have an Idea what can i do to solve this problem?



import serial
import re
serport = '/dev/ttyS1'
serbaudrate = 9600
ser = serial.Serial(port = serport, baudrate = serbaudrate, bytesize=serial.EIGHTBITS, parity=serial.PARITY_NONE, timeout=2)
try:
ser.isOpen()
except:
print("Error")
exit()

if ser.isOpen():
try:
while 1:
if ser.inWaiting() > 0:
response = ser.readline()
needles = re.match("(\d+);(\d+)", response.decode("utf-8"))
if needles:
print("Got: {} {}".format(needles[1], needles[2]))
#print("Got: {}".format(needles[2]))
else:
ser.write(b"1")
except Exception as e:
print(e)

[spjackson]

Welcome to the forums.

I haven't done serial comms in Python, but I suspect you don't have read/write permission to the device. Typically, you would need to be in the group dialout. You could test for that:

ls -l /dev/ttyS*
id
cat /dev/null > /dev/ttyS1
cat /dev/ttyS1 > /dev/null

If you get "permission denied", then that will need dealing with.

You don't have the initializer inside a try/except scope.

try:
  ser.isOpen

looks a bit weird. This call isn't likely to raise an exception.

I read that isOpen is deprecated in favour of is_open.

[norobro]

Are you sure the device is on ttyS1?

$ sudo dmesg | grep ttyS
[    0.970737] 00:03: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A

[spjackson]

[Posted in error.]