Basically I'm supposed to test modbus functionality right now and for whatever reason modbus fails to read the registers every second call, ex:
Functions:
# Modbus functions
def read_system_uptime(c, ssh):
try:
# Get uptime with ubus
ssh_result = str(exec_ssh("ubus call system info", ssh))
ssh_obj = json.loads(ssh_result)
uptime = str(ssh_obj['uptime'])
regs = c.read_holding_registers(1, 2)
if (regs != None and regs[0] == 0):
result = check_match(uptime, regs[1])
logger("System uptime", uptime, regs[1], result)
elif (regs != None and regs[0] != 0):
#Check results
temp = regs[0] * 65536 + regs[1]
result = check_match(uptime, temp)
logger("System uptime", uptime, temp, result)
else:
error_logger("System hostname", "Could not read register value")
except Exception as error:
error_logger("system uptime", error)
def read_mobile_strength(c, ssh):
try:
regs = c.read_holding_registers(3, 2)
if regs != None:
bits = decimal_To_Binary(regs[1])
a = str(binary_To_Complement(bits)).strip()
#Check results
gsmctl = str(exec_ssh("gsmctl -q", ssh)).strip()
result = check_match(gsmctl, a)
logger("Mobile signal strength", gsmctl, a, result)
else:
error_logger("Mobile signal strength", "Could not read register value")
except Exception as error:
error_logger("Mobile signal strength", error)
def read_system_hostname(c, ssh):
try:
regs = c.read_holding_registers(7, 16)
if regs != None:
a = str(dec_to_text(regs)).strip()
#Check results
name = str(exec_ssh("uci get system.system.hostname", ssh)).strip()
result = check_match(name, a)
logger("System hostname", name, a, result)
else:
error_logger("System hostname", "Could not read register value")
except Exception as error:
error_logger("System hostname", error)
Main:
# Main fuction
def main():
#router_ip, router_port, router_username, router_password = run_args(sys.argv[1:])
ssh = paramiko.SSHClient()
if ssh_connect(ssh, router_ip, router_port, router_username, router_password) != False:
modbus = modbus_start(router_ip, modbus_port, modbus_id)
if modbus != False:
read_system_hostname(modbus, ssh)
read_system_uptime(modbus, ssh)
read_mobile_strength(modbus, ssh)
# Run main()
if __name__ == '__main__':
main()
If I run the code like this, I won't get value for system uptime.
if modbus != False:
read_system_hostname(modbus, ssh)
read_mobile_strength(modbus, ssh)
read_system_uptime(modbus, ssh)
And Now I won't get mobile strength value, this happens with every second function, I can move those functions around, like move them to first position and it will work, so it's not functions fault, my guess it's pyModbusTCP or maybe even the devices that I'm working with fault, but I am not sure. Anybody knows how to deal with this? Because I never worked with this library before. Do I have to clear out the data I read or something like that? Currently I have one stupid solution of just placing a "Fake" function that reads the register and does nothing with it and place it in between others, so important ones would work, but I would like to avoid that if possible.
EDIT:
Modbus start function:
def modbus_start(ip, port, device):
try:
client = ModbusClient(host=ip, port=port, unit_id=device, auto_open=True)
print("Modbus client start: Success")
logging.info("Started Modbus client")
return client
except Exception as error:
print("ERROR: Failed to start Modbus client: ")
print(error)
logging.error("Failed to start Modbus client: %s", error)
return False
Related
I am using the following function to implement a program that changes its behavior depending on the IP of the connected PC.
There is a problem with this function that if something tries to login and fails, it may get the IP of the failed one.
And now that we've encountered that possibility, the program is broken.
What edits do I need to make to make this function behave as expected?
import psutil
def get_ip(port=3389):
ip = ""
for x in psutil.net_connections():
if x.status == "ESTABLISHED" and x.laddr.port == port:
ip = x.raddr.ip
break
I changed the function based on Bijay Regmi's comment. Thank you. wmi was difficult for me, so I used win32evtlog to read it out little by little. I am working on improving readability and finding bugs little by little.
def systime(xml):
return datetime.fromisoformat(xml.find(f'{ns}System/{ns}TimeCreated').get('SystemTime')[:-2] + "+00:00")
def last_event(handle,
event_id,
condition: Callable[['Event'], bool] = None) -> Optional['Event']:
now = datetime.now(tz=timezone.utc)
while True:
events = win32evtlog.EvtNext(handle, 20)
if not events:
break
for event in events:
xml_content = win32evtlog.EvtRender(event, win32evtlog.EvtRenderEventXml)
obj = Event(ET.fromstring(xml_content))
if obj.EventID == event_id:
if obj.SystemTime + timedelta(minutes=5) < now:
return None
if condition and not condition(obj):
continue
return obj
class Event:
def __init__(self, xml: ET.Element):
self.EventID = xml and xml.find(f'{ns}System/{ns}EventID').text
self.SystemTime = xml and systime(xml)
self.xml = xml
if self.EventID == '24':
self.IpAddress = xml.find(f'{ns}UserData/{{Event_NS}}EventXML/{{Event_NS}}Address').text
elif self.EventID == '4624':
self.IpAddress = xml.find(f'{ns}EventData/{ns}Data[#Name="IpAddress"]').text
else:
self.IpAddress = None
I am running a script that acts as a server, allows two clients to connect to it, and for one specific client to send a message to the server, the server modifies it, then sends it to the other client.
This appears to work, as the receiving client acknowledges that the input was received and is valid. This is a script that I intend to run continuously.
However, a big issue is that my /tmp/ directory is filling up with directories named _M... (The ellipses representing a random string), that contains python modules (such as cryptography, which, as far as I'm aware, I'm not using), and timezone information (quite literally every timezone that python supports). It seems to be creating them very frequently, but I can't identify what in the process exactly is doing this.
I have created a working cleanup bash script that removes files older than 5 minutes from the directory every 5 minutes, however, I cannot guarantee that when I am duplicating this process for other devices, that the directories will have the same name formatting. Rather than create a unique bash script for each process that I create, I'd rather be able to clean up the directories from within the python script, or even better, to prevent the directories from being created at all.
The problem is, I'm not certain of how this is accomplished, and I do not see anything on SO regarding what is creating these directories, nor how to delete them.
The following is my script
import time, socket, os, sys, re, select
IP = '192.168.109.8'
PORT = [3000, 3001]
PID = str(os.getpid())
PIDFILE = "/path/to/pidfile.pid"
client_counter = 0
sockets_list = []
def runCheck():
if os.path.isfile(PIDFILE):
return False
else:
with open(PIDFILE, 'w') as pidfile:
pidfile.write(PID)
return True
def openSockets():
for i in PORT:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((IP, i))
s.listen(1)
sockets_list.append(s)
def receiveMessage(client_socket):
try:
message = client_socket.recv(2048).decode('utf-8')
if not message:
return False
message = str(message)
return message
except:
return False
def fixString(local_string):
#processes
return local_string
def main():
try:
openSockets()
clients = {}
print(f'Listening for connections on {IP}:{PORT[0]} and {PORT[1]}...')
client_count = 0
while True:
read_sockets, _, exception_sockets = select.select(sockets_list, [], sockets_list)
for notified_socket in read_sockets:
if notified_socket == sockets_list[0] or notified_socket == sockets_list[1]:
client_socket, client_address = sockets_list[client_count].accept()
client_count = (client_count + 1) % 2
sockets_list.append(client_socket)
clients[client_socket] = client_socket
print('Accepted new connection from: {}'.format(*client_address))
else:
message = receiveMessage(notified_socket)
if message is False:
continue
message = fixString(message)
for client_socket in clients:
if client_socket != notified_socket:
if message != "N/A":
client_socket.send(bytes(message, "utf-8"))
for notified_socket in exception_sockets:
sockets_list.remove(notified_socket)
del clients[notified_socket]
time.sleep(1)
except socket.timeout:
for i in sockets_list:
i.close()
os.remove(PIDFILE)
sys.exit()
except Exception as e:
for i in sockets_list:
i.close()
err_details = str('Error in line {}'.format(sys.exc_info()[-1].tb_lineno), type(e).__name__, e)
os.remove(PIDFILE)
print("Exception: {}".format(err_details))
sys.exit()
if __name__ == "__main__":
if runCheck():
main()
else:
pass
How might I set it up so that the python script will delete the directories it creates in the /tmp/ directory, or better, to not create them in the first place? Any help would be greatly appreciated.
As it would turn out, it is PyInstaller that was generating these files. In the documentation, it states that pyinstaller generates this _MEI directory when creating the executable in single-file mode, and it is supposed to delete it as well, but for some reason it didn't.
So I'm building this socket application, and it works just fine on my computer. But when i start server socket on another laptop, it just crashes with a invalid start byte error:
How do i proper encode the program to work with all laptops
This is the error i get on :
Other laptops.
My laptop.
I have tried to change the encoding, but I'm just not quite sure where i have to change it.
Class Listener:
def __init__(self):
self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.server_address = (socket.gethostbyname(socket.gethostname()), 10000)
self.sock.bind(self.server_address)
print(f"LISTENER : {str(self.server_address[0])} port {str(self.server_address[1])}")
def listen(self):
self.sock.listen(1)
while True:
print("Connection Open")
print(" Waiting for connections")
self.connection, self.client_address = self.sock.accept()
try:
print(f"Connection from {str(self.client_address)}")
while True:
data = self.connection.recv(1024)
if data:
message = str(data)
if not "print" in message.lower(): # This just checks if the client wants to print system information from the server
Validate(message) # this checks for a command the server have to do
else:
self.connection.sendall(pickle.dumps(self.computerinfomation))
else:
self.listen()
except Exception as e:
print(e)
I want it to work on other laptops as well, and i just cant see why it wont.
Furas came with a solution.
I changed the
message = str(data)
to
message = str(data, encoding="utf-8")
I did the same on the client side
Not going to lie. I just changed the encoding = utf-16.
Example:
df = pd.read_csv(C:/folders path/untitled.csv, encoding = "utf-16")
I am trying to establish a two-way communication via Python3. There is a laser range finder plugged into one of my USB ports and I'd like to send/receive commands to that. I have a sheet of commands which can be sent and what they would return, so this part is already there.
What I need is a convenient way to do it in real-time. So far I have the following code:
import serial, time
SERIALPORT = "/dev/ttyUSB0"
BAUDRATE = 115200
ser = serial.Serial(SERIALPORT, BAUDRATE)
ser.bytesize = serial.EIGHTBITS #number of bits per bytes
ser.parity = serial.PARITY_NONE #set parity check: no parity
ser.stopbits = serial.STOPBITS_ONE #number of stop bits
ser.timeout = None #block read
ser.xonxoff = False #disable software flow control
ser.rtscts = False #disable hardware (RTS/CTS) flow control
ser.dsrdtr = False #disable hardware (DSR/DTR) flow control
ser.writeTimeout = 0 #timeout for write
print ("Starting Up Serial Monitor")
try:
ser.open()
except Exception as e:
print ("Exception: Opening serial port: " + str(e))
if ser.isOpen():
try:
ser.flushInput()
ser.flushOutput()
ser.write("1\r\n".encode('ascii'))
print("write data: 1")
time.sleep(0.5)
numberOfLine = 0
while True:
response = ser.readline().decode('ascii')
print("read data: " + response)
numberOfLine = numberOfLine + 1
if (numberOfLine >= 5):
break
ser.close()
except Exception as e:
print ("Error communicating...: " + str(e))
else:
print ("Cannot open serial port.")
So in the above code I am sending "1" which should trigger "getDistance()" function of the laser finder and return the distance in mm. I tried this on Putty and it works, returns distances up to 4 digits. However, when I launch the above Python script, my output is only the following:
Starting Up Serial Monitor
Exception: Opening serial port: Port is already open.
write data: 1
read data:
and it goes forever. There is no read data or whatsoever.
Where am I mistaken?
Apparently much more simpler version of the code solved the issue.
import serial
import time
ser = serial.Serial('/dev/ttyUSB0', 115200, timeout = 1) # ttyACM1 for Arduino board
readOut = 0 #chars waiting from laser range finder
print ("Starting up")
connected = False
commandToSend = 1 # get the distance in mm
while True:
print ("Writing: ", commandToSend)
ser.write(str(commandToSend).encode())
time.sleep(1)
while True:
try:
print ("Attempt to Read")
readOut = ser.readline().decode('ascii')
time.sleep(1)
print ("Reading: ", readOut)
break
except:
pass
print ("Restart")
ser.flush() #flush the buffer
Output, as desired:
Writing: 1
Attempt to Read
Reading: 20
Restart
Writing: 1
Attempt to Read
Reading: 22
Restart
Writing: 1
Attempt to Read
Reading: 24
Restart
Writing: 1
Attempt to Read
Reading: 22
Restart
Writing: 1
Attempt to Read
Reading: 26
Restart
Writing: 1
Attempt to Read
Reading: 35
Restart
Writing: 1
Attempt to Read
Reading: 36
It seems to me that your ser.timeout = None may be causing a problem here. The first cycle of your while loop seems to go through fine, but your program hangs when it tries ser.readline() for the second time.
There are a few ways to solve this. My preferred way would be to specify a non-None timeout, perhaps of one second. This would allow ser.readline() to return a value even when the device does not send an endline character.
Another way would be to change your ser.readline() to be something like ser.read(ser.in_waiting) or ser.read(ser.inWaiting()) in order to return all of the characters available in the buffer.
try this code
try:
ser = serial.Serial("/dev/ttyS0", 9600) #for COM3
ser_bytes = ser.readline()
time.sleep(1)
inp = ser_bytes.decode('utf-8')
print (inp)
except:
pass
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.