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PySerial Attributes - Issues, Documentation Current Reference?

I am very new, learning Python specifically geared toward hardware (serial port and TCP/IP device) testing.
I have been trying to get PySerial based code to work and keep hitting roadblocks. Running Python 3.10.8 on Windows 10.
I worked through the 'import serial' problem (uninstalled and reinstalled Python); the serial.Serial problem (needed to add 'from serial import *). Now, it seems like all of the read syntax does not work. All I want to do at this point is open the port, read and print data - from here I will start working on which data I want).
Here is the code I am working with (this was found in a couple of places on the internet):
#test_sport
import serial
from serial import *
s = serial.Serial(port='COM9', baudrate=9600)
serial_string = ""
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
serial_string = serial.readline()
# Print the contents of the serial data
print(serial_string.decode('Ascii'))
# Tell the device connected over the serial port that we recevied the data!
# The b at the beginning is used to indicate bytes!
#serialPort.write(b"Thank you for sending data \r\n")
Running this results in an error on serialPort.in_waiting (says serialPort not defined) if I change that to serial.in_waiting (says serial has no attribute 'in_waiting' (PySerial API site says this is correct(?). I've also tried simple commands like serial.read(), serial.readline(), ser.read(), etc. All fail for attributes.
Is the PySerial documentation online current? Does anyone know where to find basic serial port examples?
Thank you!

Python pyserial one write delay

I'm having a weird issue with pyserial, using Python 3.6.9, running under WSL Ubuntu 18.4.2 LTS
I've set up a simple function to send GCODE commands to a serial port:
def gcode_send(data):
print("Sending: " + data.strip())
data = data.strip() + "\n" # Strip all EOL characters for consistency
s.write(data.encode()) # Send g-code block to grbl
grbl_out = s.readline().decode().strip()
print(grbl_out)
It sort of works, but every command I send is 'held' until the next is sent.
e.g.
I send G0 X0 > the device doesn't react
I send G0 X1 > the device reacts to G0 X0
I send G1 X0 > the device reacts to G0 X1
and so on...
My setup code is:
s = serial.Serial(com, 115200)
s.write("\r\n\r\n".encode()) # Wake up grbl
time.sleep(2) # Wait for grbl to initialize
s.flushInput() # Flush startup text in serial input
I can work around the delay for now, but it's quite annoying and I can't find anyone else experiencing the same. Any idea what could be causing this?

There might be a lot of problems here, but rest assured that the pyserial is not causing it. It uses the underlying OS's API to communicate with the UART driver. That being said you first have to test your code with real Linux to see whether WSL is causing it. I.e. whether a Linux and Windows UART buffers are correctly synced.
I am sorry that I cannot tell whether a problem is in your code or not because I do not know the device you are using, so I cannot guess what is happening on its end of communication channel. Have in mind that Windows alone can act weirdly in best of circumstances, so, prepare yourself for some frustrations here. Check your motherboard or USB2Serial converter drivers or whatever hw you are using.
Next thing, you should know that sometimes, communication gets confusing if timeouts aren't set. Why? Nobody really knows. So try setting timeouts. Check whether you need software Xon/Xoff turned on or not, and other RS232 parameters that might be required by the device you are communicating with.
Also, see what is going on with s.readline(), I wouldn't personally use it. Timeouts might help or you can use s.read(1024) with timeouts. I do not remember right now, but see whether pyserial supports asynchronous communication. If it does, you can try using it instead of standard blocking mode.
Also, check whether you have to forcefully flush the serial buffer after s.write() or add a sleep after it. It might happen that the device doesn't get the message but the read request is activated. As the device didn't receive the command it doesn't respond. After you send another command, IO buffer is flushed and the previous one is delivered and so forth. Serial communication is fun, but when it hits a snag it can be a real P in the A, believe me.
Ow, a P.S. Check whether the device sends "\r\n\r\n" or "\r\n" only, or "\r" or "\n" in response. s.readline() might get confused. For a start, try putting there two s.readline()s one after another and print out each output. If the device sends double EOL then the one s.readline() is stopping on the empty line and your program receives an empty response, when you send another command s.readline() goes through the buffer and returns a full line that is already there but not read before.

Here it goes. The code promissed in the comment. Big portions of it removed and error checks too.
It is a typing terminal for using PyS60 Python console on Nokia smartphones in the Symbian series via bluetooth. Works fantastically.
from serial import *
from thread import start_new_thread as thread
from time import sleep
import sys, os
# Original code works on Linux too
# The following code for gettin one character from stdin without echoing it on terminal
# has its Linux complement using tricks from Python's stdlib getpass.py module
# I.e. put the terminal in non-blocking mode, turn off echoing and use sys.stdin.read(1)
# Here is Win code only (for brevity):
import msvcrt
def getchar ():
return msvcrt.getch()
def pause ():
raw_input("\nPress enter to continue . . .")
port = raw_input("Portname: ")
if os.name=="nt":
nport = ""
for x in port:
if x.isdigit(): nport += x
port = int(nport)-1
try:
s = Serial(port, 9600)
except:
print >> sys.stderr, "Cannot open the port!\nThe program will be closed."
pause()
sys.exit(1)
print "Port ready!"
running = 1
def reader():
while running:
try:
msg = s.read()
# If timeout is set
while msg=="":
msg = s.read()
sys.stdout.write(msg)
except: sleep(0.001)
thread(reader,())
while 1:
try: c = getchar()
except Exception, e:
running = 0
print >> sys.stderr, e
s.write('\r\n\x04')
break
if c=='\003' or c=='\x04':
running = 0
s.write('\r\n\x04')
break
s.write(c)
s.close()
pause()

Connecting via USB/Serial port to Newport CONEX-PP Motion Controller in Python

I'm having trouble getting my Windows 7 laptop to talk to a Newport CONEX-PP motion controller. I've tried python (Spyder/Anaconda) and a serial port streaming program called Termite and in either case the results are the same: no response from the device. The end goal is to communicate with the controller using python.
The controller connects to my computer via a USB cable they sold me that is explicitly for use with this device. The connector has a pair of lights that blink when the device receives data (red) or sends data (green). There is also a packaged GUI program that comes with the device that seems to work fine. I haven't tried every button, the ones I have tried have the expected result.
The documentation for accessing this device is next to non-existant. The CD in the box has one way to connect to it and the webpage linked above has a different way. The first way (CD from the box) creates a hierarchy of modules that ends in a module it does not recognize (this is a code snippet provided by Newport):
import sys
sys.path.append(r'C:\Newport\MotionControl\CONEX-PP\Bin')
import clr
clr.AddReference("Newport.CONEXPP.CommandInterface")
from CommandInterfaceConexPP import *
import System
instrument="COM5"
print 'Instrument Key=>', instrument
myPP = ConexPP()
ret = myPP.OpenInstrument(instrument)
print 'OpenInstrument => ', ret
result, response, errString = myPP.SR_Get(1)
That last line returns:
Traceback (most recent call last):
File "< ipython-input-2-5d824f156d8f >", line 2, in
result, response, errString = myPP.SR_Get(1)
TypeError: No method matches given arguments
I'm guessing this is because the various module references are screwy in some way. But I don't know, I'm relatively new to python and the only time I have used it for serial communication the example files provided by the vendor simply worked.
The second way to communicate with the controller is via the visa module (the CONEX_SMC_common module imports the visa module):
import sys
sys.path.append(r'C:\Newport\NewportPython')
class CONEX(CONEXSMC): def __init__(self):
super(CONEX,self).__init__() device_key = 'com5'
self.connect=self.rm.open_resource(device_key, baud_rate=57600, timeout=2000, data_bits=8, write_termination='\r\n',read_termination='\r\n')
mine.connect.read()
That last mine.connect.read() command returns:
VisaIOError: VI_ERROR_TMO (-1073807339): Timeout expired before operation completed.
If, instead, I write to the port mine.connect.write('VE') the light on the connector flashes red as if it received some data and returns:
(4L, < StatusCode.success: 0 >)
If I ask for the dictionary of the "mine" object mine.__dict__, I get:
{'connect': <'SerialInstrument'(u'ASRL5::INSTR')>,
'device_key': u'ASRL5::INSTR',
'list_of_devices': (u'ASRL5::INSTR',),
'rm': )>}
The ASRL5::INSTR resource for VISA is at least related to the controller, because when I unplug the device from the laptop it disappears and the GUI program will stop working.
Maybe there is something simple I'm missing here. I have NI VISA installed and I'm not just running with the DLL that comes from the website. Oh, I found a Github question / answer with this exact problem but the end result makes no sense, the thread is closed after hgrecco tells him to use "open_resource" which is precisely what I am using.
Results with Termite are the same, I can apparently connect to the controller and get the light to flash red, but it never responds, either through Termite or by performing the requested action.
I've tried pySerial too:
import serial
ser = serial.Serial('com5')
ser.write('VE\r\n')
ser.read()
Python just waits there forever, I assume because I haven't set a timeout limit.
So, if anyone has any experience with this particular motion controller, Newport devices or with serial port communication in general and can shed some light on this problem I'd much appreciate it. After about 7 hours on this I'm out of ideas.

After coming back at this with fresh eyes and finding this GitHub discussion I decided to give pySerial another shot because neither of the other methods in my question are yet working. The following code works:
import serial
ser = serial.Serial('com5',baudrate=115200,timeout=1.0,parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE, bytesize=serial.EIGHTBITS)
ser.write('1TS?\r\n')
ser.read(10)
and returns
'1TS000033\r'
The string is 9 characters long, so my arbitrarily chosen 10 character read ended up picking up one of the termination characters.
The problem is that python files that come with the device, or available on the website are at best incomplete and shouldn't be trusted for anything. The GUI manual has the baud rate required. I used Termite to figure out the stop bit settings - or at least one that works.

3.5 years later...
Here is a gist with a class that supports Conex-CC
It took me hours to solve this!
My device is Conex-CC, not PP, but it's seem to be the same idea.
For me, the serial solution didn't work because there was absolutely no response from the serial port, either through the code nor by direct TeraTerm access.
So I was trying to adapt your code to my device (because for Conex-CC, even the code you were trying was not given!).
It is important to say that import clr is based on pip install pythonnet and not pip install clr which will bring something related to colors.
After getting your error, I was looking for this Pythonnet error and have found this answer, which led me to the final solution:
import clr
# We assume Newport.CONEXCC.CommandInterface.dll is copied to our folder
clr.AddReference("Newport.CONEXCC.CommandInterface")
from CommandInterfaceConexCC import *
instrument="COM4"
print('Instrument Key=>', instrument)
myCC = ConexCC()
ret = myCC.OpenInstrument(instrument)
print('OpenInstrument => ', ret)
response = 0
errString = ''
result, response, errString = myCC.SR_Get(1, response, errString)
print('Positive SW Limit: result=%d,response=%.2f,errString=\'%s\''%(result,response,errString))
myCC.CloseInstrument()
And here is the result I've got:
Instrument Key=> COM4
OpenInstrument => 0
Positive SW Limit: result=0,response=25.00,errString=''�

For Conex-CC serial connections are possible using both pyvisa
import pyvisa
rm = pyvisa.ResourceManager()
inst = rm.open_resource('ASRL6::INSTR',baud_rate=921600, write_termination='\r\n',read_termination='\r\n')
pos = inst.query('01PA?').strip()
and serial
import serial
serial = serial.Serial(port='com6',baudrate=921600,bytesize=8,parity='N',stopbits=1,xonxoff=True)
serial.write('01PA?'.encode('ascii'))
serial.read_until(b'\r\n')
All the commands are according to the manual

python : How to detect device name/id on a serial COM

I would like some indication on how to do this in python:
Identify the port named a specific name in the serial com (\Device\VCP0 and \Device\VCP1 these are get by browsing in regedit window)
And get the id of the device that is pluged
I can already identify the avalable COM with this pySerial code that scan up the active serial port COM
import serial
def scan():
"""scan for available ports. return a list of tuples (num, name)"""
available = []
for i in range(256):
try:
s = serial.Serial(i)
available.append( (i, s.portstr))
s.close() # explicit close 'cause of delayed GC in java
except serial.SerialException:
pass
return available
if __name__=='__main__':
print "Found ports:"
for n,s in scan():
print "(%d) %s" % (n,s)
Thanks in advance

I am not sure what operating system you are using, but this is in Win7-x64
import win32com.client
wmi = win32com.client.GetObject("winmgmts:")
for serial in wmi.InstancesOf("Win32_SerialPort"):
print (serial.Name, serial.Description)
Using this information, you can parse it and get the COM numbers.
You can get other attributes of the Serial instances here:
http://msdn.microsoft.com/en-us/library/aa394413(v=vs.85).aspx

Two answer
1) Because this relies on the hardware available, it is perfectly possible that the test code worked in the environment it was written on, but doesn't work in your environment - may be quite likely if you are on Windows and this was written on Linux. The code uses port 0 - don't know how that maps to COM1 etc.
2) On Windows, COM ports used to have DOS names like COM1, COM2 - i.e. A string, not an int (they aren't like TCP/IP port numbers). More recently in Windows there is the \.\COMnotanumber format which allows a more generic name, I've seen these used by a USB to serial converter. Having had a quick look at the source code of pyserial SerialBase in serialutil.py, it's a bit odd IMO, because AFAICT self.name only gets set when you use an explicit port setting by calling self.port(portname). You might want to try intializing the serial port instance with serport = Serial(0) then explicitly calling serport.port('COM1') (or whatever your port name is instead of COM1).
Just corrected the code. its working fine... :)
import serial
def scan():
available = []
for i in range(256):
try:
s = serial.Serial('COM'+str(i))
available.append( (s.portstr))
s.close() # explicit close 'cause of delayed GC in java
except serial.SerialException:
pass
for s in available:
print "%s" % (s)
if __name__=='__main__':
print "Found ports:"
scan()

If you are using a USB to TTY serial adapter, a unique symbolic link to the device driver file will appear in /dev/serial/by-id. The folder will only appear if a serial device is plugged in. The file name displayed is created from the product information in the USB interface chip on the device and will be unique for that device.
For instance, a Korad KD3005P programmable power supply will show up as usb-Nuvoton_USB_Virtual_COM_A92014090305-if00. The symbolic link will resolve to '/../../ttyACM0'. The required device drive file is then '/dev/ttyACM0'.

Passive Serial Port Monitor

I'm using pyserial to open two ports, and then write to each what I read from the other. I then have a physical com port connected to one of these ports and a virtual com port connected to the other. The virtual com port is in turn connected to a second virtual com port to which my simulator connects:
Hardware device <> COM1 <> Python Script <> VCOM2 <> VCOM3 <> Simulator
I can see that the communication is correctly entering and exiting the com ports in my script but something isn't right since the the hardware is failing to communicate correctly with the simulator.
I have an old c app that I can run in place of the Python Script and this works correctly. However, it is really badly written and I've no real interest in fixing all its bugs. So I'm hoping I can replace this app with a python script. I eventually wish to log the data passing through the ports with a timestamp.
I am using the correct baud rate in both cases, however I seem to be missing something. Should I be transferring signals between each port, DTR for example? pyserial has these functions:
sendBreak(duration=0.25)
setBreak(level=True)
setRTS(level=True)
setDTR(level=True)
getCTS()
getDSR()
getRI()
getCD()
What signals am I interested in?
EDIT:
When I poll these values for each port:
getCTS(), getDSR(), getRI(), getCD()
I Get:
True, False, False, True COM1
False, False, False, False VCOM2
However, I see that CD becomes false sometimes. How do I transfer this out through VCOM2 or do I need to do this?
EDIT:
Here's my code. Once communication starts the script locks up and I need to restart my computer to release the port. I can't kill the associated python process on Windows 7...
import serial
class NewMonitor():
def __init__(self, com_port_1, com_port_2):
self.read_time_in_seconds = 0.1
self.serialPort1 = serial.Serial(com_port_1, 9600, timeout=self.read_time_in_seconds, rtscts=True, dsrdtr=True)
self.serialPort2 = serial.Serial(com_port_2, 9600, timeout=self.read_time_in_seconds, rtscts=True, dsrdtr=True)
try:
while True:
item = self.serialPort1.read()
self.serialPort2.write(item)
self.serialPort2.setRTS(self.serialPort1.getCTS())
self.serialPort2.setDTR(self.serialPort1.getDSR())
item = self.serialPort2.read()
self.serialPort1.write(item)
self.serialPort1.setRTS(self.serialPort2.getCTS())
self.serialPort1.setDTR(self.serialPort2.getDSR())
finally:
self.serialPort1.close()
self.serialPort2.close()

you cannot ignore the signals, especially if you use HW based flow-control. I assume that you at least have to link the following signals between both ports besides RX(read) and TX(write)
CTS -> RTS
DSR -> DTR
Comments about your code:
You defined a timeout, this means the IO function will block (even if it is only for a short amount of time). Consider setting it to 0
You call read without parameter. This will only read a single byte. Any reason why you do not want to read more at once? Would reduce the overhead.
Consider adding a condition to exit the while loop. At the moment the code will run until pyserial throws an exception.