As a newbie to python, I'm trying to use it to read a file and write each line of the file to the RS-232 port. My code bellow seems to work for the most part, except for my listen and react segments. From poking around, it seems that my if statements can't read if I've received a "Start\r", or "End\r" string from my device (RS-232). Can anyone provide feedback on what is missing?
import serial
import time
port = "/dev/ttyS0"
speed = 9600
print("\n\n\n\nScript Starting\n\n\n")
ser = serial.Serial(port, speed, timeout=0)
ser.flushInput() #flush input buffer, discarding all its contents
ser.flushOutput()#flush output buffer, aborting current output and discard all that is in buffer
text_file = open("my.file", "r")
lines = text_file.read().split('\n')
i = 0
counter = 0
while i<len(lines):
response = ser.readline()
if (counter == 0):
print("\n\nProbing With Off Data\n")
ser.write('FFF')
ser.write('\r')
counter+=1
if (response == 'Start'):
ser.write('FFF')
ser.write('\r')
if (response == 'End'):
print("\nString Transmitted:")
print lines
make_list_a_string = ''.join(map(str, lines))
ser.write(make_list_a_string)
ser.write('\r')
print("\n")
i+=1
text_file.close()
exit(0)
Try using strip() to get rid of any trailing or preceding '\r's:
if (response.strip() == 'Start'):
Related
I am writing a python script that will gather data from a serial port. I am able to gather the data and when it comes out it says b'1' I want to make an if statement for if it comes out as b'1' then I want it to run a function.
This is my code.
import serial
import time
z1baudrate = 115200
z1port = '/dev/ttyACM0'
z1serial = serial.Serial(port=z1port, baudrate=z1baudrate)
z1serial.timeout = 2
print (z1serial.is_open)
if z1serial.is_open:
while True:
size = z1serial.inWaiting()
if size:
data = z1serial.read(size)
print (data)
else:
print ("no data")
time.sleep(1)
else:
print("z1serial not open")
What should I do?
You can use "==" operator with bytes.
if z1serial.is_open == b'1':
...
should do the trick.
I am new at Python and I have been trying to figure out the following exercise.
Exercise 5: (Advanced) Change the socket program so that it only shows data after the headers and a blank line have been received. Remember that recv is receiving characters (newlines and all), not lines.
I attached below the code I came up with, unfortunately I don't think it is working:
import socket
mysocket=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
mysocket.connect(('data.pr4e.org', 80))
mysocket.send('GET http://data.pr4e.org/romeo.txt HTTP/1.0\r\n\r\n'.encode())
count=0
while True:
data = mysocket.recv(200)
if (len(data) < 1): break
count=count+len(data.decode().strip())
print(len(data),count)
if count >=399:
print(data.decode(),end="")
mysocket.close()
Instead of counting the number of lines received, just grab all the data you get and then split on the first double CRLF you find.
resp = []
while True:
data = mysocket.recv(200)
if not data: break
resp.append(data.decode())
mysocket.close()
resp = "".join(resp)
body = resp.partition('\r\n\r\n')[2]
print(body)
I'm using PySerial to read from serial port like in the code below.
CheckReadUntil() read output of the command that I send to serial port until the sequence of symbols readUntil are in the serial output.
...
self.ser = serial.Serial(comDev, 115200, timeout=10)
...
#Function that continue to read from Serial port until 'readUntil'
#sequence of symbols appears
def CheckReadUntil(self, readUntil):
outputCharacters = []
while 1:
ch = self.ser.read()
outputCharacters += ch
if outputCharacters[-len(readUntil):]==readUntil:
break
outputLines = ''.join(outputCharacters)
return outputLines
However, if there is no sequence readUntil (for any reason), I'm just stuck in the function CheckReadUntil() forever. The setting timeout=10 sets up timeout so I'm stuck in a loop that iterates every 10 seconds and does nothing, just waiting.
How it is possible to understand that there was a timeout event so I may exit the infinite loop? Output length may be different.
UPDATE (previous answer was not correct, this is the working code from #konstantin):
...
self.ser = serial.Serial(comDev, 115200, timeout=10)
...
#Function that continue to read from Serial port until 'readUntil'
#sequence of symbols appears
def CheckReadUntil(self, readUntil):
outputCharacters = []
while 1:
ch = self.ser.read()
if len(ch) == 0:
break
outputCharacters += ch
if outputCharacters[-len(readUntil):]==readUntil:
break
outputLines = ''.join(outputCharacters)
return outputLines
I'm sending a list of values (e.g. 80,539,345,677) from Arduino to a Python app running on my RPi. I have not been successful in extracting the values and assigning them to respective variables or objects in the app.
Here's my code:
def read_values():
#if DEBUG:
print "reading arduino data"
ser = serial.Serial('/dev/ttyUSB0', 9600)
print "receiving arduino data"
ser_line = ser.readline()
print ser_line
ser.close()
ser_list = [int(x) for x in ser_line.split(',')]
ambientLight = ser_list[1]
print ambientLight
return ambientLight
What I'm getting from Python is:
reading arduino data
receiving arduino data
80,477,82,2
Traceback (most recent call last):
File "serialXivelyTest4c.py", line 77, in <module>
run()
File "serialXivelyTest4c.py", line 63, in run
ambientLight = read_values()
File "serialXivelyTest4c.py", line 27, in read_values
ser_list = [int(x) for x in ser_line.split(',')]
ValueError: invalid literal for int() with base 10: '8254\r80'
You can see that I'm getting values, but that they're being truncated. Can anyone please tell me where I'm going wrong here. Thanks so much.
I've never used an Arduino but here's how I read from serial with a different board. I used serial.
import streamUtils as su # see below
ser = su.connectPort("/dev/tty.SLAB_USBtoUART") # make sure you have the right port name
data = ""
while True:
try:
data = data + ser.read(1) # read one, blocking
time.sleep(1) # give it time to put more in waiting
n = ser.inWaiting() # look if there is more
if n:
data = data + ser.read(n) # get as much as possible
# I needed to save the data until I had complete
# output.
if data:
# make sure you have the whole line and format
else:
break
except serial.SerialException:
sys.stderr.write("Waiting for %s to be available" % (ser.name))
sys.exit(1)
sys.stderr.write("Closing port\n")
ser.close()
Here's the streamUtils.connectPort():
import serial
def connectPort(portname):
# connect to serial port
ser = serial.Serial()
ser.port = portname
ser.baudrate = 9600
ser.parity = serial.PARITY_NONE
ser.stopbits = serial.STOPBITS_ONE
ser.bytesize = serial.EIGHTBITS
ser.timeout = 15 # need some value for timeout so the read will end
try:
ser.open()
except serial.SerialException:
sys.stderr.write("Could not open serial port %s\n" % (ser.name))
sys.exit(1)
return (ser)
I'm having trouble to read more than one character using my program, I can't seem to figure out what went wrong with my program.
import serial
ser = serial.Serial(
port='COM5',\
baudrate=9600,\
parity=serial.PARITY_NONE,\
stopbits=serial.STOPBITS_ONE,\
bytesize=serial.EIGHTBITS,\
timeout=0)
print("connected to: " + ser.portstr)
count=1
while True:
for line in ser.read():
print(str(count) + str(': ') + chr(line) )
count = count+1
ser.close()
here are the results I get
connected to: COM5
1: 1
2: 2
3: 4
4: 3
5: 1
actually I was expecting this
connected to: COM5
1:12431
2:12431
something like the above mentioned which is able read multiple characters at the same time not one by one.
I see a couple of issues.
First:
ser.read() is only going to return 1 byte at a time.
If you specify a count
ser.read(5)
it will read 5 bytes (less if timeout occurrs before 5 bytes arrive.)
If you know that your input is always properly terminated with EOL characters,
better way is to use
ser.readline()
That will continue to read characters until an EOL is received.
Second:
Even if you get ser.read() or ser.readline() to return multiple bytes,
since you are iterating over the return value, you will
still be handling it one byte at a time.
Get rid of the
for line in ser.read():
and just say:
line = ser.readline()
I use this small method to read Arduino serial monitor with Python
import serial
ser = serial.Serial("COM11", 9600)
while True:
cc=str(ser.readline())
print(cc[2:][:-5])
Serial sends data 8 bits at a time, that translates to 1 byte and 1 byte means 1 character.
You need to implement your own method that can read characters into a buffer until some sentinel is reached. The convention is to send a message like 12431\n indicating one line.
So what you need to do is to implement a buffer that will store X number of characters and as soon as you reach that \n, perform your operation on the line and proceed to read the next line into the buffer.
Note you will have to take care of buffer overflow cases i.e. when a line is received that is longer than your buffer etc...
EDIT
import serial
ser = serial.Serial(
port='COM5',\
baudrate=9600,\
parity=serial.PARITY_NONE,\
stopbits=serial.STOPBITS_ONE,\
bytesize=serial.EIGHTBITS,\
timeout=0)
print("connected to: " + ser.portstr)
#this will store the line
line = []
while True:
for c in ser.read():
line.append(c)
if c == '\n':
print("Line: " + ''.join(line))
line = []
break
ser.close()
I was reciving some date from my arduino uno (0-1023 numbers).
Using code from 1337holiday, jwygralak67 and some tips from other sources:
import serial
import time
ser = serial.Serial(
port='COM4',\
baudrate=9600,\
parity=serial.PARITY_NONE,\
stopbits=serial.STOPBITS_ONE,\
bytesize=serial.EIGHTBITS,\
timeout=0)
print("connected to: " + ser.portstr)
#this will store the line
seq = []
count = 1
while True:
for c in ser.read():
seq.append(chr(c)) #convert from ANSII
joined_seq = ''.join(str(v) for v in seq) #Make a string from array
if chr(c) == '\n':
print("Line " + str(count) + ': ' + joined_seq)
seq = []
count += 1
break
ser.close()