#Qt serial port baud rate install
#Qt serial port baud rate serial
#Qt serial port baud rate code

The signal has to be in a class definition, and must specify the type of data that will be attached: class MyWidget(QWidget):

#Qt serial port baud rate serial

We could use the same technique for received data the serial thread could add it to a queue that is polled by the UI thread, and somehow trigger a UI redraw when the new data arrives, but I prefer to use a signal the data is attached to that signal, and is received by a UI function that has registered a connection. So the serial thread polls the transmit queue for any data, outputting it to the serial port. Instead, weвЂ™ll use a First In First Out (FIFO) queue: # In UI thread. That means we canвЂ™t just use a global shared string variable Python does a lot of behind-the-scenes processing that could lead to an unpredictable result. The user will be entering keystrokes in the UI thread, and it is tempting to call the serial transmit function from that thread, but this isnвЂ™t a good idea it is better to pass the keystrokes across to the serial thread for transmission, and we need a thread-safe method of doing this. When the application is closing, it terminates the thread by setting the boolean variable false, then (very importantly) waits for the thread to finish its execution: def closeEvent(self, event): I use a global variable, that can be set false to terminate, e.g. The run() method needs to keep running in a perpetual loop, but it must be possible to terminate that loop when the program exits вЂ“ Python wonвЂ™t do it automatically. Print('Opening %s at %u baud' % (self.portname, self.baudrate)) I have chosen to supply the serial parameters (port name & baud rate) when the thread object is instantiated, so they are available when the thread is started this is done by calling the start() method, which will call a run() method in the QThread class: # In serial thread: Self.portname, self.baudrate = portname, baudrate Creating a new thread is really easy in Python you just subclass QThread, and instantiate it: class SerialThread(QtCore.QThread): Threading allows the UI to carry on interacting with the user, while simultaneously keeping the serial link alive. At best, this makes the application appear sluggish and unresponsive at worst, it can appear to have failed, waiting for a response that never comes. Without threading (or any other mitigation scheme) the User Interface (UI) will lock up after each command, waiting for the response.

The key problem with serial communications is the time it takes the slower the data rate, the longer the delay before anything happens.

#Qt serial port baud rate install

YouвЂ™ll need to install pySerial by the usual methods (e.g.

Return d if type(d) is str else ''.join() This can lead to all sorts of problems (such as unwanted exceptions) so IвЂ™ve included specific functions to ensure that all outgoing data is converted from the internal representation (which could be Unicode) to a string of bytes, and incoming data is converted from the external type (data bytes or string) to a string type: # Convert a string to bytes (for Python 3) There is also an issue with the different ways Python 2 and 3 handle serial data older versions assume that the data type is an ASCII string, while in later versions it is a binary type. This necessitates some rather clunky inclusions at the top of the file: try:ДЇrom PyQt4.QtGui import QTextEdit, QWidget, QApplication, QVBoxLayoutДЇrom PyQt5.QtWidgets import QTextEdit, QWidget, QApplication, QVBoxLayout

#Qt serial port baud rate code

My code is compatible with Python 2.7 and 3.x, PyQt v4 and v5, running on Windows or Linux. It wonвЂ™t win any awards for style, but could come in handy next time you encounter an obscure serial protocol.

The following blog describes a simple Windows & Linux serial terminal, that can be adapted to handle special protocols it also demonstrates the creation of Python threads, and can serve as a basis for other multi-threaded applications.

I do a lot of work with serial comms TeraTerm is an excellent serial terminal, but sometimes a customised application is required, for example when dealing with binary data. A simple demonstration of threading in PyQt