m trying to create a tool that help to simulate key press
but at part of this code mentioned below, the program gets stuck and its not proceeding
ser = serial.Serial(ACM)
ser.baudrate = 115200
ser.timeout = None
ser.flushInput()
ser.flushOutput()
ser.write(cmd)
p = ser.readline()
pr = p.decode("utf-8")
print(cmd)
print(pr)
ser.close()
print("Closed")
" ser.readline() is not reading the output of serial com /dev/ttyACM*
Thanks
The PySerial documentation is unmistakable:
Be careful when using readline(). Do specify a timeout when opening
the serial port otherwise it could block forever if no newline
character is received.
You define: ser.timeout = None so what exactly do you expect your program to do, but block forever if you don't receive a newline?
Either make sure the sent lines are terminated or use a reasonable timeout.
Related
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.
I am currently doing research and writing a simple program in controlling a camera through the serial port, RS-422 to be more specific. I got the camera control protocol documentation from the manufacturer. I've been reading and testing for a few days now but unfortunately, I haven't managed to make it work. I used Python (3.7) to speed up the testing. Below is my sample code:
import serial
ser_port = serial.Serial(
port='COM4',
baudrate=9600,
parity=serial.PARITY_NONE,
stopbits=serial.STOPBITS_ONE,
bytesize=serial.EIGHTBITS
)
sccp_cmd_null = [0x00]
sccp_cmd = [0xE7, 0x40, 0x11, 0x43, 0x00, 0x00] # Chroma Key "GREEN"
if ser_port.isOpen():
# Try sending a break code first
try:
print("Sending Break Code: ", serial.to_bytes(sccp_cmd_null))
ser_port.write(serial.to_bytes(sccp_cmd_null))
except:
print("Failed Sending Break Code!")
# Try Sending The Commands
try:
print("Sending Commands: ", serial.to_bytes(sccp_cmd))
ser_port.write(serial.to_bytes(sccp_cmd))
except:
print("Failed Sending Commands!")
ser_port.close()
Please note that this is my first time writing code that deals with Serial Ports.
Thank you in advanced for those who can provide help ^_^
I have written a UART py-serial script, which looks like.
import serial
import time
try:
ser = serial.Serial(
#port='/dev/ttyAMA0',
port='/dev/ttyUSB1',
baudrate = 9600,
parity=serial.PARITY_NONE,
stopbits=serial.STOPBITS_ONE,
bytesize=serial.EIGHTBITS,
timeout=2
)
print ('Connection is open : ',str(ser.isOpen()))
except Exception as e:
print ("Something got wrong: ", e)
ser.write(b'hello..')
and have a similar script as receiver.
what I want is:
suppose timeout = 5
ser.write(b'Helloo...')
ser.flush()
ser.readline()
the other script is reading it and sending a response via serial only.
this readline should wait maximum for this timeout, if it received response in 2 seconds then it should not wait for 5seconds.
But using this timeout it waits for 2 seconds, even if the data is received in a second.
so my concern is to wait maximum for timeout, but if data received earlier it should end and proceed.
Not able to find this functionality, please help.
found a way for this to work:
pyserial have this inbuit functionality, for eg:
ser.read_until(b'#') #just specify EOL here
It will break if this (#) is found. if not, will wait for timeout and return at end.
You can also use seperate timeouts for read and write:
timeout=5 #read timeout
write_timeout=5 # write timeout
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 been trying to send a value from a Python program via serial to an Arduino, but I have been unable to get the Arduino to store and echo back the value to Python. My code seems to match that I've found in examples online, but for whatever reason, it's not working.
I am using Python 3.5 on Windows 10 with an Arduino Uno. Any help would be appreciated.
Arduino code:
void readFromPython() {
if (Serial.available() > 0) {
incomingIntegrationTime = Serial.parseInt();
// Collect the incoming integer from PySerial
integration_time = incomingIntegrationTime;
Serial.print("X");
Serial.print("The integration time is now ");
// read the incoming integer from Python:
// Set the integration time to what you just collected IF it is not a zero
Serial.println(integration_time);
Serial.print("\n");
integration_time=min(incomingIntegrationTime,2147483648);
// Ensure the integration time isn't outside the range of integers
integration_time=max(incomingIntegrationTime, 1);
// Ensure the integration time isn't outside the range of integers
}
}
void loop() {
readFromPython();
// Check for incoming data from PySerial
delay(1);
// Pause the program for 1 millisecond
}
Python code:
(Note this is used with a PyQt button, but any value could be typed in instead of self.IntegrationTimeInputTextbox.text() and the value is still not receieved and echoed back by Arduino).
def SetIntegrationTime(self):
def main():
# global startMarker, endMarker
#This sets the com port in PySerial to the port with the Genuino as the variable arduino_ports
arduino_ports = [
p.device
for p in serial.tools.list_ports.comports()
if 'Genuino' in p.description
]
#Set the proper baud rate for your spectrometer
baud = 115200
#This prints out the port that was found with the Genuino on it
ports = list(serial.tools.list_ports.comports())
for p in ports:
print ('Device is connected to: ', p)
# --------------------------- Error Handling ---------------------------
#Tell the user if no Genuino was found
if not arduino_ports:
raise IOError("No Arduino found")
#Tell the user if multiple Genuinos were found
if len(arduino_ports) > 1:
warnings.warn('Multiple Arduinos found - using the first')
# ---------------------------- Error Handling ---------------------------
#=====================================
spectrometer = serial.Serial(arduino_ports[0], baud)
integrationTimeSend = self.IntegrationTimeInputTextbox.text()
print("test value is", integrationTimeSend.encode())
spectrometer.write(integrationTimeSend.encode())
for i in range(10): #Repeat the following 10 times
startMarker = "X"
xDecoded = "qq"
xEncoded = "qq"
while xDecoded != startMarker: #Wait for the start marker (X))
xEncoded = spectrometer.read() #Read the spectrometer until 'startMarker' is found so the right amound of data is read every time
xDecoded = xEncoded.decode("UTF-8");
print(xDecoded);
line = spectrometer.readline()
lineDecoded = line.decode("UTF-8")
print(lineDecoded)
#=====================================
spectrometer.close()
#===========================================
#WaitForArduinoData()
main()
First, this is a problem:
incomingValue = Serial.read();
Because read() returns the first byte of incoming serial data reference. On the Arduino the int is a signed 16-bit integer, so reading only one byte of it with a Serial.read() is going to give you unintended results.
Also, don't put writes in between checking if data is available and actual reading:
if (Serial.available() > 0) {
Serial.print("X"); // Print your startmarker
Serial.print("The value is now ");
incomingValue = Serial.read(); // Collect the incoming value from
That is bad. Instead do your read immediately as this example shows:
if (Serial.available() > 0) {
// read the incoming byte:
incomingByte = Serial.read();
That's two big issues there. Take care of those and let's take a look at it after those fundamental issues are corrected.
PART 2
Once those are corrected, the next thing to do is determine which side of the serial communication is faulty. Generally what I like to do is determine one side is sending properly by having its output show up in a terminal emulator. I like TeraTerm for this.
Set your python code to send only and see if your sent values show up properly in a terminal emulator. Once that is working and you have confidence in it, you can attend to the Arduino side.