I have just tried to connect to usb mobile to send sms through it using AT commands. But when i use pyserial to connect to it in a windows os, i get error could not open port, the file specified cannot be found.
>>> import serial
>>> ser = serial.Serial(0) # open first serial port
>>> print ser.name # check which port was really used
>>> ser.write("hello") # write a string
>>> ser.close()
even if i replace the 0 with any other value, like 0 -10 or 'com0','com1' etc, i still get error file specified not found, port cannot be open.
There is a command listed in pyserial documentation which lists ports or allows you to open a port
python -m serial.tools.miniterm
This command is supposed to list all serial ports. But it shows none.
I have 3 usb ports on my system. What is causing this issue.
Pyserial is not guaranteed to detect all ports. This depends on how the device and the OS communicate and if pyserial is designed to pick up on this. For Example, pyserial could not detect a LabJack U3-LV or a EPSOM-POS receipt printer I plugged in in a Win8 session (both could be detected using a linux session).
Try serial.tools.list_ports.comports() and see what it gives you.
You could also look at the pyusb module for usb connections.
Also: I recommend being careful when using numbers for ports, as the mapping may not be "common-sense" logical (i.e. 0 may not map to COM0). Use explicit string names instead.
I found the solution myself. Its pretty simple and uses the same code in the question.. I was getting blocked error because there was no modem(nokia phone) in my device manager. although i had plugged in my phone into the usb, there was no nokia pc suite installed. Once you install nokia pc suite and connect your nokia phone, in device manager -> modems your phone will appear. Just check its properties->modem and you will find the com5 or whichever number. Then use that id to connect. If you dont know this, just iterate till you find the right one.
Thanks everyone who tried to help
Related
I need to run both zigbee and SMS dongle on a raspberry pi, that means having to run both ports in a python script. Since xbee is always on ttyUSB0, is there a way I could set the dongle on ttyUSB1 or ttyUSB2 so that i dont have to configure it via gammu command everytime it is plugged in?
The best thing to do here is use a udev rule. This will allow you to symlink the device to a specific port, something like /dev/ttyXBEE and /dev/ttySMS in your case.
To accomplish this, you need to query the devices using udevadm to find some unique identifying information, then create a file /etc/udev/rules.d/99-usbserial.rules that will tell the Pi how to map the device.
This thread has an example.
I have a device with a built-in USB/Serial adapter (shows up as a Prolific PL2303). The device documentation provides full details on how to communicate with it, and provides a sample Windows app. However, I need to use it on Linux - ideally with Python but I'm not too precious about that.
The device docs state the device runs at 9600, 8N1 with half duplex. The Windows app works fine - device works fine (so I know it's not a device problem). However, I can't communicate with it using Python on Linux. I'm using pySerial, and I've tried a similar (full duplex, also PL2303) device which works fine.
I've tried several combinations of setting xonxoff, rtscts etc. I've also tried RTS toggling using setRTS(True) and checking for CTS and DSR etc - gets all return False. I can successfully open the device using pySerial (I can see activity light flashing - simple but effective test) and pySerial complains if you unplug it during reads/writes.
Doesn't seem to matter what flags/lines I set or what data I send, always get the same result.
>>> s=serial.Serial()
>>> s.port('/dev/ttyUSB1')
>>> s.open()
>>> s
Serial<id=0x7fe94b533b50, open=True>(port='/dev/ttyUSB1', baudrate=9600, bytesize=8, parity='N', stopbits=1, timeout=3, xonxoff=0, rtscts=0, dsrdtr=0)
>>> s.write('\2CMD2292\r')
>>> s.inWaiting()
0
>>> s.setRTS(True)
>>> s.getCTS()
False
(several iterations of above with different flags).
Ignore the data in the write command - that's just a status check command. Doesn't matter what goes there, the device should either respond with an answer or an error.
I've even resorted to closing and re-opening the device in between setting various ctsrts flags etc., and unplugging / replugging it to force resets. As above it continues to work fine using the Windows test app. I can't use Portmon etc. to sniff the Windows port traffic as it's a 64bit Win7 install and I don't currently have time to build an XP machine.
Any thoughts?
UPDATE: I've also tried all of the above using Python on the same Windows box that the demo app works on. It definitely opens the port and communicates, but again no info back regardless of what's written.
UPDATE2: It looks like it might be device-driver related. Some additional background research suggests that some PL2303 chips have functionality to support half-duplex, but this isn't supported by the Linux drivers. The Windows demo app comes with a dedicated device driver and the app doesn't work on a clean test machine using default Windows drivers. This makes me think that while I can connect to it successfully through Python, I can't control the duplex comms (e.g. even in an STX/ETX way) and therefore this might be a hopeless case. sigh.
UPDATE3: Thanks for the comments below. However, I couldn't find any way round this. I tried a USB protocol analyser, and I tried disassembling the driver but it just became rather time-consuming, so in the end I took the device apart and after some tinkering I managed to replace the existing usb-serial adapter with a proper PL2303 part - on the device side, it was just a basic 2-wire serial interface so it didn't care what was talking to it. I can't seem to close this question so I'll leave it as-is.
Try
s.flush()
just after your s.write call
The solution to this problem is probably pretty simple, but I am new to interfacing with a device dynamically. What I'm doing is I am making a python executable code, so the user doesn't have to have Idle on their computer or any kind of python interpreter, which means I don't know which USB port the device will be plugged in to. The program needs to be able to open a connection to a device that is connected through a serial to usb converter. How can I determine which connected device is the correct device to open a port to? I am using pySerial to interact with the device. Any help would be greatly appreciated.
No matter how you configure your device, at some point you're probably going to have to ask the user where the port is, or poll all serial devices for a known response. (Polling has it's pitfalls though, so read on!). Unlike USB devices, there is no vendor/device ID that is made known to the OS when you attach a plain-old serial device.
First you need to find the serial ports. Here's a question that might help: What is the cross-platform method of enumerating serial ports in Python (including virtual ports)?.
Once you have a list of serial ports, you could ask the user whether they know which one to use. If they do, problem solved!
If they don't, you could offer to poll ALL serial devices with some data that you know will yield a certain response from your device. Keep in mind though that if the user has other serial devices attached, your string of "hello" bytes might actually be the self-destruct sequence for some other device! Hence, you should warn the user that polling may interfere with other devices, and always prompt them before you do so.
Without knowing more about your code (eg. what comms framework, if any, you're using; are you doing this in the console or are you using a GUI toolkit, etc), it's impossible to say what the best way to code this might be. In the simplest case, you could just loop over all of your serial devices, send the greeting and check for a response. (You could also do this in parallel: loop once for the greeting, and loop again to check what's in the buffer. If you're going to get more fancy than that, use a proper library.)
Side note: You might be able to get around this if you have a built-in converter that you can set the vendor/device ID for, but the converter will still be automatically detected by any modern OS and enumerated as a serial port; you won't get to talk to it directly as a USB device. It could be possible to figure out which port goes with which ID, but I've never tried to do that. But this approach is useless if you're not the one who gets to pick the converter (eg. if it's a user-supplied cable).
This is the way that I used for identify Serial-USB conveter device like Arduino.
It checks 'USB' String of device description.
import serial as ser
import serial.tools.list_ports as prtlst
global COMs
COMs=[]
def getCOMs():
global COMs
pts= prtlst.comports()
for pt in pts:
if 'USB' in pt[1]: #check 'USB' string in device description
COMs.append(pt[0])
The only way I can think to get around the problem with probing unknown devices is to have the device send unsolicited "hello" responses continually. That was you can just connect to all serial devices and listen for the "hellos". Connecting and listening to a serial device shouldn't ever mess it up.
The downside is you have these messages cluttering up your serial stream. You could have a "I'm here now, stfu" command but then you can only connect to it once.
FTDI chips have a method of identification but you have to use their library to access the data.
I have an 2-port signal relay connected to my computer via a USB serial interface. Using the pyserial module I can control these relays with ease. However, this is based on the assumption that I know beforehand which COM-port (or /dev-node) the device is assigned to.
For the project I'm doing that's not enough since I don't want to assume that the device always gets assigned to for example COM7 in Windows. I need to be able to identify the device programatically across the possible platforms (Win, Linux, OSX (which I imagine would be similar to the Linux approach)), using python. Perhaps by, as the title suggests, enumerate USB-devices on the system and somehow get more friendly names for them. Windows and Linux being the most important platforms to support.
Any help would be greatly appreciated!
EDIT:
Seems like the pyudev-module would be a good fit for Linux-systems. Has anyone had any experience with that?
Regarding Linux, if all you need is to enumerate devices, you can even skip pyudev dependency for your project, and simply parse the output of /sbin/udevadm info --export-db command (does not require root privileges). It will dump all information about present devices and classes, including USB product IDs for USB devices, which should be more then enough to identify your USB-to-serial adapters. Of course, you can also do this with pyudev.
I know this is an older post, but I was struggling with it today.
Ultimately I used the wmi library for python as I'm on a Windows machine (sorry, I know my answer only applies to Windows, but maybe it'll help someone).
Install the package using pip first:
pip install wmi
then
import wmi
c = wmi.WMI()
wql = "Select * From Win32_USBControllerDevice"
for item in c.query(wql):
print item.Dependent.Caption
Should result with something like:
USB Root Hub
USB Root Hub
Prolific USB-to-Serial Comm Port (COM9)
USB Root Hub
USB Root Hub
USB Composite Device
USB Video Device
USB Audio Device
USB Root Hub
...snip...
In this case, you'd have to string parse the Caption to find the COM port. You can also take a look at just the item. Dependent object to see other attributes of the USB device beside Caption that you may find relevant:
instance of Win32_PnPEntity
{
Caption = "USB Root Hub";
ClassGuid = "{36fc9e60-c465-11cf-8056-444553540000}";
ConfigManagerErrorCode = 0;
ConfigManagerUserConfig = FALSE;
CreationClassName = "Win32_PnPEntity";
Description = "USB Root Hub";
DeviceID = "USB\\ROOT_HUB\\4&32F13EF0&1";
HardwareID = {"USB\\ROOT_HUB&VID8086&PID3A36&REV0000",
"USB\\ROOT_HUB&VID8086&PID3A36", "USB\\ROOT_HUB"};
Manufacturer = "(Standard USB Host Controller)";
Name = "USB Root Hub";
PNPDeviceID = "USB\\ROOT_HUB\\4&32F13EF0&1";
Service = "usbhub";
Status = "OK";
SystemCreationClassName = "Win32_ComputerSystem";
SystemName = "001fbc0934d1";
};
At least for linux, you can use some dummy hacks to determine your /dev node, by inspecting for example the output of "ls /dev | grep ttyUSB" before and after you attach your device. This somehow must apply as well for the OSX case. A good idea is to inspect those commands using something like the subprocess.Popen() command. As for windows, this might be helpful.
Windows: you can pull USB information from WMI, but you need to be administrator. The examples are in .NET, but you should be able to use the Python WMI module. This will give you access to USB identification strings, which may contain useful information. For FTDI serial devices there is a short cut using FTDI's DLL, which does not require privileged access.
Linux: all the available information is under /sys/bus/usb, and also available through udev. This looks like a good answer.
As far as Windows goes, you could scan the registry:
import _winreg as reg
from itertools import count
key = reg.OpenKey(reg.HKEY_LOCAL_MACHINE, 'HARDWARE\\DEVICEMAP\\SERIALCOMM')
try:
for i in count():
device, port = reg.EnumValue(key, i)[:2]
print device, port
except WindowsError:
pass
It will be great if this is possible, but in my experience with commercial equipments using COM ports this is not the case. Most of the times you need to set manually in the software the COM port. This is a mess, specially in windows (at least XP) that tends to change the number of the com ports in certain cases. In some equipment there is an autodiscovery feature in the software that sends a small message to every COM port and waits for the right answer. This of course only works if the instrument implements some kind of identification command. Good luck.
In Hyperterminal I am able to connect to a serial port called "X64-CL_iPro_1_Serial_0" where I am able to send/receive ASCII text to a camera. However when I try to connect to the same port with pySerial, it throws an exception:
SerialException: could not open port X64-CL_iPro_1_Serial_0: [Error 2] The system cannot find the file specified.
I don't understand why Hyperterminal can detect the port and communicate with it, but Python can't. I downloaded this script from the pySerial website that displays a list of serial ports, and the only ports it came up with was COM1 and COM2, neither of which I can connect to.
My code is very simple, and looks like this:
import serial
port = "X64-CL_iPro_1_Serial_0"
ser = serial.Serial(port)
Am I doing anything wrong? Is there a way to work around this? Thanks ahead of time.
Edit:
It should also be noted that this port does not show up in the device manager, and neither does COM1 or COM2.
The problem lies in the enumeration code you linked. It is wrong in two regards:
It uses a fixed GUID_CLASS_COMPORT to enumerate. It should instead ask the GUID through SetupDiClassGuidsFromName, passing "Ports" as description of the class for which it is asking for names.
The code insists of asking for the friendly name of the port. But if the only goal is to open the device (instead of displaying to an user), it should directly access the DevicePath element, which is a weird-looking-but-perfectly-valid port name to pass to pySerial. The friendly name might even be totally missing.
aside
I'm not clear the question is about non-serial-port use through pyserial, or serial port that is not a COMX port in enumeration.
This may be a bit OT or too hard code for your use, but here goes first, using some other file in a pyserial object:
foo = serial.Serial()
peer = serial.Serial()
foo.fd, peer.fd = posix.openpty()
try: foo._isOpen = peer._isOpen = True # depending on pyserial version
except: pass
foo._reconfigurePort()
peer.setTimeout(timeout=0.1)
peer._reconfigurePort()
Regarding second, remember that ports beyond COM9 use weird windows notation \\.\COM10, perhaps that's what Hyperterminal does for you. pyserial doesn't do it, so perhaps you need to open the port something like this:
s = serial.Serial("\\\\.\\X64-CL_iPro_1_Serial_0") # also remember to escape backslash