Devices used : Beaglebone_AI and 2 STM32 nucleos connected to the Beaglebone AI using USB hub.
The idea:
The Beaglebone uses a python3 script that uses multiprocessing and pyserial to create 3 processes:
Process 1 - Request a string from STM32 #1 and adds the string to FIFO Queue
Process 2 - Function that writes all responses from STM32 #2
Process 3 - .get() from FIFO Queue go through a switch statement to process either strings from STM32 #1 or user commands.
The Problem:
- It seems like sometimes pyserial .write() dosnt send the user command or data.
can Pyserial .read() and .write() at the same time ??
This is my function process that prints everything that it receives:
def writeall(serial_port, q2):
all_bytes = []
while True:
try:
bytesToRead = serial_port.inWaiting()
data = serial_port.read(bytesToRead).decode('utf-8')
if not data:
pass
else:
if data == '\n':
data = ''.join(all_bytes)
#Print to screen everything
print(data, end = '\033[K\n\n', flush=True)
all_bytes.clear()
#serial_port.reset_input_buffer()
else:
#append all the bytes that are being received
all_bytes.append(str(data))
except (OSError,serial.serialutil.SerialException) as e:
print(f'Actuator Controller: {e}') ```
**This is my serial port config:**
``` def opening_port(q2):
global serial_port
try:
a =""
for p in ports:
#if 'COM9' in p.device: #for windows
if "066BFF343633464257245637" in p.serial_number: #my nucleo
a = p.device
# Port initialization
serial_port = serial.Serial(
port= a,
baudrate=9600,
bytesize= serial.EIGHTBITS,
parity= serial.PARITY_NONE,
stopbits= serial.STOPBITS_ONE,
timeout= 1)
# Discarding anything in the I/O buffer.
#serial_port.reset_output_buffer()
#serial_port.reset_input_buffer()
return serial_port ```
**ANd this is pyserial .write() function that uses the same port as the writeall function process**
``` def write_comand(comand):
try:
#Reset the buffer before sending a command
serial_port.reset_output_buffer()
serial_port.reset_input_buffer()
serial_port.write(bytes(comand,'utf8'))
# Testing wheter the Queue is getting the user commands and if we are actually sending them
if '3E12' in str(comand):
pass
else :
print(f" cmd sent {comand}\n")
#time.sleep(0.005)
except (OSError,serial.serialutil.SerialException) as e:
print (f" There was a problem communicating with AC: {e}\n")
print('Resetting Actuator Controller...\n')
write_comand('B6D8\r')# reset command ```
Related
I am currently trying to read the output of writing a command to the serial port where my USB device is connected.
import pyserial
ser = serial.Serial(port=portName,baudrate=19200,parity=serial.PARITY_NONE,stopbits=serial.STOPBITS_ONE,bytesize=serial.EIGHTBITS)
ser.xonxoff = 0
ser.rtscts = 0
ser.set_buffer_size(rx_size=256, tx_size=256)
ser.writeTimeout = 2
ser.timeout = 2
ser.write("\r".encode())
if not ser.is_open:
ser.open()
try:
ser.flushInput()
ser.flushOutput()
ser.write(command.encode())
return ser.readlines()
finally:
ser.close()
I always have to run this code twice in order to execute a command. What parameter should I change here in order to not have this issue?
I am wanting to interrupt this bluetooth connect in a programmable way in python if I can. I have read many articles online and cannot seem to find a way to send an interrupt, other than a keyboard interrupt, to the client_sock, clientInfo = server_sock.accept() so that this line of code stops its bluetooth connectivity. The end game is to use my GUI side of this program by implementing a "Stop Connection" button in my GUI to halt the bluetooth connection. Is there a way to do that in python3 at all, or is this something that can only be handled via command line???
size = 1024
while True:
self.bluetooth_information.append("Waiting for connection")
self.bluetooth_information.append(str(datetime.now().time()))
client_sock, clientInfo = server_sock.accept()
try:
data = client_sock.recv(size) # receives data from client
if len(data) == 0:
break
client_sock.send(self.parse.process_data(data)) # Echo response back to client
# except bluetooth.btcommon.BluetoothError:
# pass
if self.stop:
client_sock.close()
server_sock.close()
self.stop = False
self.bluetooth_information.clear()
break
except KeyboardInterrupt:
client_sock.close()
server_sock.close()
break
I have light detector sensors connected to a data acquisition box and it is connected to my laptop via RS232 usb cable. I have stabilized serial communication to that port in python. But when I try to read the data it just keeps on running and it doesn't display any value. I have tried this same think in MATALB and it works properly, so I know that port and sensors are working fine. I am just not able to read the data in python. I have three ways(shown below in python code) but nothing works. Please help me.
Here is my python code:
import serial
from serial import Serial
s = serial.Serial('COM3') # open serial port
print(ser.name)
# Set the serial port to desired COM
s = serial.Serial(port = 'COM3', bytesize = serial.EIGHTBITS, parity = serial.PARITY_NONE, baudrate = 9600, stopbits = serial.STOPBITS_ONE)
# Read the data(method 1)
while 1:
while (s.inWaiting() > 0):
try:
inc = s.readline().strip()
print(inc)
# Read the data(method 2)
data = str(s.read(size = 1))
print(data)
# Read all the data(method 3)
while i <10:
b = s.readlines(100) # reading all the lines
in matlab it gave values with a space but in same line
That indicates there are no newline characters sent by the device.
I've never used your device or the Python serial module. But from the docs, this is what I would do:
from time import sleep
while s.is_open():
n = s.in_waiting()
if n == 0:
print "no data"
sleep(1)
continue
try:
inc = s.read(n)
print(inc)
catch serial.SerialException as oops:
print(oops)
catch serial.SerialTimeoutException as oops:
print(oops)
print("serial port closed")
This gives you feedback for each condition: port open/closed, data ready/not, and the data, if any. From there you can figure out what to do.
The documentation says inWaiting is deprecated, so I used in_waiting.
I wouldn't be surprised if the problem lies in configuring the serial port in the first place. Serial ports are tricky like that.
This question is two-fold.
1. So I need to run code for a socket server that's all defined and created in another.py, Clicking run on PyCharm works just fine, but if you exec() the file it just runs the bottom part of the code.
There are a few answers here but they are conflicting and for Python 2.
From what I can gather there are three ways:
- Execfile(), Which I think is Python 2 code.
- os.system() (But I've seen it be said that it's not correct to pass to the OS for this)
- And subprocess.Popen (unsure how to use this either)
I need this to run in the background, it is used to create threads for sockets for the recv portion of the overall program and listen on those ports so I can input commands to a router.
This is the complete code in question:
import sys
import socket
import threading
import time
QUIT = False
class ClientThread(threading.Thread): # Class that implements the client threads in this server
def __init__(self, client_sock): # Initialize the object, save the socket that this thread will use.
threading.Thread.__init__(self)
self.client = client_sock
def run(self): # Thread's main loop. Once this function returns, the thread is finished and dies.
global QUIT # Need to declare QUIT as global, since the method can change it
done = False
cmd = self.readline() # Read data from the socket and process it
while not done:
if 'quit' == cmd:
self.writeline('Ok, bye. Server shut down')
QUIT = True
done = True
elif 'bye' == cmd:
self.writeline('Ok, bye. Thread closed')
done = True
else:
self.writeline(self.name)
cmd = self.readline()
self.client.close() # Make sure socket is closed when we're done with it
return
def readline(self): # Helper function, read up to 1024 chars from the socket, and returns them as a string
result = self.client.recv(1024)
if result is not None: # All letters in lower case and without and end of line markers
result = result.strip().lower().decode('ascii')
return result
def writeline(self, text): # Helper func, writes the given string to the socket with and end of line marker at end
self.client.send(text.strip().encode("ascii") + b'\n')
class Server: # Server class. Opens up a socket and listens for incoming connections.
def __init__(self): # Every time a new connection arrives, new thread object is created and
self.sock = None # defers the processing of the connection to it
self.thread_list = []
def run(self): # Server main loop: Creates the server (incoming) socket, listens > creates thread to handle it
all_good = False
try_count = 0 # Attempt to open the socket
while not all_good:
if 3 < try_count: # Tried more than 3 times without success, maybe post is in use by another program
sys.exit(1)
try:
self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # Create the socket
port = 80
self.sock.bind(('127.0.0.1', port)) # Bind to the interface and port we want to listen on
self.sock.listen(5)
all_good = True
break
except socket.error:
print('Socket connection error... Waiting 10 seconds to retry.')
del self.sock
time.sleep(10)
try_count += 1
print('Server is listening for incoming connections.')
print('Try to connect through the command line with:')
print('telnet localhost 80')
print('and then type whatever you want.')
print()
print("typing 'bye' finishes the thread. but not the server",)
print("eg. you can quit telnet, run it again and get a different ",)
print("thread name")
print("typing 'quit' finishes the server")
try:
while not QUIT:
try:
self.sock.settimeout(0.500)
client = self.sock.accept()[0]
except socket.timeout:
time.sleep(1)
if QUIT:
print('Received quit command. Shutting down...')
break
continue
new_thread = ClientThread(client)
print('Incoming Connection. Started thread ',)
print(new_thread.getName())
self.thread_list.append(new_thread)
new_thread.start()
for thread in self.thread_list:
if not thread.isAlive():
self.thread_list.remove(thread)
thread.join()
except KeyboardInterrupt:
print('Ctrl+C pressed... Shutting Down')
except Exception as err:
print('Exception caught: %s\nClosing...' % err)
for thread in self.thread_list:
thread.join(1.0)
self.sock.close()
if "__main__" == __name__:
server = Server()
server.run()
print('Terminated')
Notes:
This is created in Python 3.4
I use Pycharm as my IDE.
One part of a whole.
2. So I'm creating a lightning detection system and this is how I expect it to be done:
- Listen to the port on the router forever
The above is done, but the issue with this is described in question 1.
- Pull numbers from a text file for sending text message
Completed this also.
- Send http get / post to port on the router
The issue with this is that i'm unsure how the router will act if I send this in binary form, I suspect it wont matter, the input commands for sending over GSM are specific. Some clarification may be needed at some point.
- Recieve reply from router and exception manage
- Listen for relay trip for alarm on severe or close strike warning.
- If tripped, send messages to phones in storage from text file
This would be the http get / post that's sent.
- Wait for reply from router to indicate messages have been sent, exception handle if it's not the case
- Go back to start
There are a few issues I'd like some background knowledge on that is proving hard to find via the old Google and here on the answers in stack.
How do I grab the receive data from the router from another process running in another file? I guess I can write into a text file and call that data but i'd rather not.
How to multi-process and which method to use.
How to send http get / post to socket on router, post needed occording to the router manual is as follows: e.g. "http://192.168.1.1/cgi-bin/sms_send?number=0037061212345&text=test"
Notes: Using Sockets, threading, sys and time on Python 3.4/Pycharm IDE.
Lightning detector used is LD-250 with RLO Relay attached.
RUT500 Teltonica router used.
Any direction/comments, errors spotted, anything i'm drastically missing would be greatly appreciated! Thank you very much in advance :D constructive criticism is greatly encouraged!
Okay so for the first part none of those suggested in the OP were my answer. Running the script as is from os.system(), exec() without declaring a new socket object just ran from __name__, this essentially just printed out "terminated", to get around this was simple. As everything was put into a classes already, all I had to do is create a new thread. This is how it was done:
import Socketthread2
new_thread = Socketthread2.Server() # Effectively declaring a new server class object.
new_thread.run()
This allowed the script to run from the beginning by initialising the code from the start in Socket, which is also a class of Clientthread, so that was also run too. Running this at the start of the parent program allowed this to run in the background, then continue with the new code in parent while the rest of the script was continuously active.
I have a TCP client communicating with a LabVIEW GUI.
My program calls connect() at the start and disconnect() at the end. It will call passCommand(x) to read or write data to the LabVIEW GUI. However, in some cases, I have multiple threads which may be calling passCommand() and somehow the return data will get mixed up.
For example, in the main thread I will ask for the voltage, which should be a number between 300 and 400. In a different thread I will ask for the temperature, which should be a number from 0-100. The voltage will be returned as 25, while the temperature will get 250.
Is this a known issue with TCP communication and threading? Is there a way to solve this such as implementing a queue or unique id or something?
import socket as _socket
# get python major version as integer
from sys import version as pythonVersion
pythonVersionMajor = int(pythonVersion[0])
_serverHost = 'localhost'
_serverPort = 50007
isConnected = 0
_sockobj = None
_error_string = "error:"
def connect():
'opens a connection to LabVIEW Server'
global _sockobj, isConnected
_sockobj = _socket.socket(_socket.AF_INET, _socket.SOCK_STREAM) # create socket
_sockobj.connect((_serverHost, _serverPort)) # connect to LV
isConnected = 1
def disconnect():
'closes the connection to LabVIEW Server'
global isConnected
_sockobj.close() # close socket
isConnected = 0
def passCommand(command):
'passes a command to LabVIEW Server'
## We prepend the command length (8 char long) to the message and send it to LV
# Compute message length and pad with 0 on the left if required
commandSize=str(len(command)).rjust(8,'0')
# Prepend msg size to msg
completeCommand=commandSize+command
# python 3 requires data to be encoded
if (pythonVersionMajor >= 3):
completeCommand = str.encode(completeCommand)
# Send complete command
_sockobj.send(completeCommand)
data = _sockobj.recv(11565536)
# python 3 requires data to be decoded
if (pythonVersionMajor >= 3):
data = bytes.decode(data)
if data.rfind(_error_string) == 0:
error = True
data = data[len(_error_string):] # get data after "error:" string
else:
error = False
execString = "lvdata = " + data
exec(execString, globals())
if error:
raise _LabVIEWError(lvdata)
else:
return lvdata
class _Error(Exception):
"""Base class for exceptions in this module."""
pass
class _LabVIEWError(_Error):
"""Exception raised for errors generated in LabVIEW.
Attributes:
code -- LabVIEW Error Code
source -- location of the error
message -- explanation of the error
"""
def __init__(self, error):
self.code = error[0]
self.source = error[1]
self.message = error[2]
def __str__(self):
return "%s" % (self.message,)
This is an example of one of the most common problems with threading. You are accessing a resource from multiple threads and the resource is not considered thread-safe (if both threads are sending/receiving at the same time, it's possible for a thread to get the wrong response, or even both responses).
Ideally you should be locking access to passCommand with a mutex so it can only be used with by one thread at a time, or opening one socket per thread, or doing all of your socket operations in a single thread.