I have a terminal which I connect to with serial communication, and I want to read from it and write to it some commands I prepared in advance in a string array
Using pySerial, I need to write a code that will read the lines with a stop condition which is a wait from the console for input from the user, and then write the commands from the array
Just want to clarify, it's like an automatic PuTTY, and no I can't connect to the terminal through ssh, and no I can't bood the machine's terminal since it's not a pc
here is what i tried:
import serial
Baud_Rate = 9600
Ser = serial.Serial('COM4', Baud_Rate)
while Ser.isOpen():
input('Error: Ser is already open, please close it manually. if the port is
closed, press enter\n')
try:
Ser.close()
except serial.serialutil.PortNotOpenError:
pass
Ser.open()
Serial_com = [] #a str array with the relevant commands
for i in range(len(Serial_com)):
ter = Ser.readline()
while ter != 0xaf:
#print(str(ter))
print(str(ter.decode('utf-8').rstrip('\r\n')))
ter = Ser.readline()
sleep(1)
if i == 0:
print('login: root')
Ser.write(bytes("root", encoding='utf-8'))
else:
print('\n\n\n\n\nroot # Ser: ~ # ' + str(Serial_com[i]))
Ser.write(bytes(Serial_com[i], encoding='utf8'))
I realized that once the serial port is waiting for the python code (or the user) to write commands, that it sends the character 0xaf. It might be a coincidence, but still I wrote that as a stop condition for the reading from the terminal
the code can read from the serial port, but once it needs to write to the serial port it won't proceed
I can't share the rest because it's confedencial for a project
Related
(update)
So I found some documentation on this link
https://elinux.org/RPi_Serial_Connection#Connections_and_signal_levels
If you scroll down you will find a section "S/W: Preventing Linux from using the serial port" It says "By default Linux will grab the serial port and use it as a terminal."
So it appears that this is a thing, however, the instructions it gives is for a Raspberry Pi, and it calls for you to use raspi-config. It doesn't give anything for regular linux use.
Using python I'm attempting to communicate between my laptop and an Up-Board. I'm connecting the Up-board by using an FTDI cable, connected to the serial connection on the board.
(OP)
I've done something similar before with C++ on a different board. The code I'm using I pulled from this site, http://www.varesano.net/blog/fabio/serial%20rs232%20connections%20python
import time
import serial
ser = serial.Serial(
port='/dev/ttyUSB0',
baudrate=115200,
parity=serial.PARITY_NONE,
stopbits=serial.STOPBITS_ONE,
bytesize=serial.EIGHTBITS
)
print ser.isOpen()
input=1
while 1 :
input = raw_input(">> ")
print "Check"
try:
if input == 'exit':
ser.close()
exit()
else:
ser.write(input + '\r\n')
out = ''
time.sleep(1)
while ser.inWaiting() > 0:
out += ser.read(1)
if out != '':
print ">>" + out
except:
ser.close()
break
I'm doing something similar on the Up-board. The only difference is that it waits for a message, then returns the message back to my laptop. Just a loop back between the Upboard and my laptop.
Here's where it gets interest.
I'm having two seperate issues.
1) I'll attempt to send a word, ie "test" and it will only send "e", "tst" doesn't get sent
2) The other issue is, it sends message, and I get a return for a password. So I reset the software and attempt to connect again, this time I send the username as the first message. I get back a reply for password, then I send the password, and now I have terminal access to the Upboard. While, all I really want is to connect to the application on the other end.
Does anyone have any suggestions on what is going on?
So I found the resolution, it appears that the system was configured in grub to connect to terminal on the same port address.
if you go to /etc/default/grub you will find a line
GRUB_CMDLINE_LINUX="console=ttyS0, 115200n8"
I ended up commenting that line, and I now can connect without it giving me console control.
I am trying to open a serial port connection and keep it open as long as data if communicating. I also want to respond if certain data is received. Below is an example of the python script. I am able to open the serial port send data and the script responds, it will not respond with the elif data.
I am new to pyserial and have been working on python lately but not great by any means.
Thank you
import serial
import time
ser = serial.Serial('/dev/ttyUSB0', timeout=10) # open serial port
print(ser.name) # check which port was really used
response = ser.read()
if response == (b'\r'):
ser.write (b'ID=')
elif response == (b'\r\r\x1bPG1\r'):
ser.write (b'110 1.8<CR><ACK><CR><ESC>[p<CR>')
#time.sleep(5)
#print ()
#ser.close() # close port
I have Python 3.6.1 and PySerial Installed. I am trying the
I am able to get the list of comports connected. I now want to be able to send data to the COM port and receive responses back. How can I do that? I am not sure of the command to try next.
Code:
import serial.tools.list_ports as port_list
ports = list(port_list.comports())
for p in ports:
print (p)
Output:
COM7 - Prolific USB-to-Serial Comm Port (COM7)
COM1 - Communications Port (COM1)
I see from the PySerial Documentation that the way to open a COM Port is as below:
import serial
>>> ser = serial.Serial('/dev/ttyUSB0') # open serial port
>>> print(ser.name) # check which port was really used
>>> ser.write(b'hello') # write a string
>>> ser.close() # close port
I am running on Windows and I get an error for the following line:
ser = serial.Serial('/dev/ttyUSB0')
This is because '/dev/ttyUSB0' makes no sense in Windows. What can I do in Windows?
This could be what you want. I'll have a look at the docs on writing.
In windows use COM1 and COM2 etc without /dev/tty/ as that is for unix based systems. To read just use s.read() which waits for data, to write use s.write().
import serial
s = serial.Serial('COM7')
res = s.read()
print(res)
you may need to decode in to get integer values if thats whats being sent.
On Windows, you need to install pyserial by running
pip install pyserial
then your code would be
import serial
import time
serialPort = serial.Serial(
port="COM4", baudrate=9600, bytesize=8, timeout=2, stopbits=serial.STOPBITS_ONE
)
serialString = "" # Used to hold data coming over UART
while 1:
# Wait until there is data waiting in the serial buffer
if serialPort.in_waiting > 0:
# Read data out of the buffer until a carraige return / new line is found
serialString = serialPort.readline()
# Print the contents of the serial data
try:
print(serialString.decode("Ascii"))
except:
pass
to write data to the port use the following method
serialPort.write(b"Hi How are you \r\n")
note:b"" indicate that you are sending bytes
I have trouble reading an arbitrary port with pySerial. I can only read the port when the port hasn't been used by any program after it's turned on. Otherwise, I can open the port but ser.inWaiting() returns 0, telling me there is no data in the port buffer. Actually, I can see data in a port monitor, so why does pySerial gets no data? I am using os x 10.9.5., python 2.7.8 and pySerial 2.7
Here is the code:
def usb():
ser = serial.Serial('/dev/tty.usbmodem422651', 115200)
try:
while True:
print ser.read(1000)
except KeyboardInterrupt:
ser.close()
exit
if __name__ == "__main__":
testUSB()
Thank you for your help!
You need to understand how serial works.
If you already opened some terminal and read the data, then it's the input buffer of the serial port is now empty.
while True:
print ser.read(1000)
It's not a good practice, you can try the following using inWating:
if ser.inWaiting:
ser.read(len(ser.inWaiting()))
You cannot open the port from 2 different apps or software.
A good code will look like:
import serial
def my_usb():
s_handle = serial.Serial('/dev/tty.usbmodem422651', 115200)
# or any other end condition
while True:
try:
if s_handle.inWaiting():
print s_handle.read(s_handle.inWaiting())
except KeyboardInterrupt:
print "exiting...."
finally:
s_handle.close()
if __name__ == "__main__":
my_usb()
I have a device (Pololu Wixel) that I'm trying to communicate with using a serial connection over USB. Hyperterminal works fine but I'm trying to use Python for more flexibility. I can send commands to the device, but when I try to receive all I get is the command I just sent. However, if I open Hyperterminal, I'll receive the reply there to the command sent from the script. My code is below. I'm at a bit of a loss and it seems like this should be fairly straightforward. I appreciate any help.
import serial
import time
'''
Go through 256 COM ports and try to open them.
'ser' will be the highest port number. Fix this later.
'''
for i in range(256):
currentPort = "COM" + str(i+1)
try:
ser = serial.Serial(currentPort,baudrate=115200,timeout=5)
print("Success!!")
print(ser.name)
except:
pass
print(ser.isOpen())
str = "batt" #Command to request battery levels.
ser.write(str.encode())
x = ser.inWaiting()
print(x)
while ser.inWaiting() > 0:
out = ser.readline()
print(out.decode())
Add a break after finding an active port,
Try passing a different eol value to readline(), "\r" or "\r\n".