Here at ULPGC I'm following a Robotics course. In the practical part of the exam we have to write some applications to operating some didactics robots we have (Rhino XR-4 and SCARA Robots).
Each robot is connected to a Controller (Rhino Mark-4) which can be connected to a PC to send commands to the Controller in order to let the robots do things.
The PC to Controller connection is a serial RS-232 connection. 12 step rummy card game.
- Python Serial Port Extension Brought to you. I think the inWaiting code has not changed since several releases. The constant TIOCINQ it uses, is retrieved differently in 2.7, but it gives the same value on my system. Software or power supply on the MCU side that makes the USB device appear and disappear for example?
- /dev/tty706 opened with 4800 baud. Timeout is None seconds. Waiting for start indicator (0).Found. Reading data until EOM.127.126.125.124.123.122.121.120.
- Aug 16, 2018.
- Reading serial data in realtime in Python. You are waiting for the timeout at each reading since it waits for eol. The serial input Q remains the same it just a. Do specify a timeout when opening the serial port otherwise it could block forever if no. Do also have a look at the example files in the examples directory in the.
To know the version of python run. Python -version. If the pip command is available (run pip to see if return or not command not found bash) run (replace with pip2 and pip3 based on the python version used). Sudo install pyserial pip3. Otherwise through apt-get. Sudo apt-get install python-serial python3-serial Read on the serial port Free.
So. for the practical parts of the exams we need to write applications which, using the RS-232 communication channels, controls the movements of the robots.
The professor here suggested to use Java to implement the applications: unfortunately I found the API comm pretty complex in installation and configuration.
So. I looked for different solutions.
Surprisingly I found that Python with the pySerial module is a pretty intelligent solution!
I've been able to install and use them (in both Linux and Windows) without problems at all (while my classmates had lot of problems with java and comm apis..). Just follow any guide on the web to install Python on your system and then follow the pySerial installation guide.
Using the pySerial apis is pretty simple: just have a look at the project website to have an idea of the apis it gives you.
A simple application
I give you here a simple application which should let you understand how python serial apis are easy to use. The application is a simple serial terminal which you can use to send commands (and receive output) to a serial connected device.
This is the application code: Latest ie for xp.
NOTE for Python 3 users: The code above has been written for Python 2 and I'm no more able to test RS232 connections with Python 3. As some users commented below the raw_input() function has been removed so you should just use the new Python 3 function input(). If you use Python 3 and find other issues with the code please leave a comment. Thanks!
As you can see the code is pretty simple and self documenting. This should demonstrate you the power of this solution.
Really important is the serial port configuration: if you configure it incorrectly you probably will end in problems during communications (check the manual of the device you are connecting to get the correct connections parameters).
Also remember to point the port parameter to the device file you are using (under windows you can simply use COMMX, where X is the COMM instance number 1,2,3,4,etc. )
Conclusions
I consider Python and pySerial one of the simplest and faster ways to develop an application to use a serial connection.
You will also be able to use the huge amounts of other native apis and additional modules Python has to add all kind of features to you applications!
If you need a graphical interface I strongly encourage you to have a look at the pyGTK project and the Glade interface designer.
pySerial is a Python API module to access the serial port. pySerialprovides a uniform API across multiple operating systems, includingWindows, Linux, and BSD. This article explains how to use the pySerialAPI to access a serial port.
Installation
The following procedure installs pySerial in GNU/LinuxSystems. pyserial installs a package serial and can be used frompython.
Download pyserial from http://pypi.python.org/pypi/pyserial.Extract the archive file and run:
for Python 3.x:
From the Python Package Index
or
Using pySerial API
For using this package in python, we have to import a module calledserial. Enter in to python Interpreter by running the command python
Opening a Serial Port
- The opened serial port is /dev/ttyUSB0
- You can see the serial object was created with default baudrate 9600.
- Which has 8 bit mask, no parity is None and 1 stop bit
- Timeout is 0
- Software flow control off (xonxoff = false)
- Hardware flow control off (rtscts = False, dsrdtr = False)
Examples to Change serial attributes
We can change the properties of the serial portat any time after opening the port.
- dir(ser) will show all attributes for the ser object
- help(serial.Serial) will show the man page for serial API’s
- You can see the modifed serial attributes by using ser .
- Like wise you can modify all the attributes as per the requirement
Python Serial In Waiting Example Pdf
Writing Data
- write(data) will write the string data to the port and returns no. of bytes sent.
Reading Data
Python Serial Inwaiting
- read(size) will read data from serial port
- A time out can be set, so that within that time if no characters are received, read() will return an empty string. If timout is None, read() won’t return until it receives the no. of bytes specified as argument.
- readline(size) will read a line until it sees a EOL(end of line n) character.
- It also read up to the size of bytes. Pokemon liquid crystal walkthrough pdf download.
- Suppose the serial device sending a data rnSerial Uploadrn
- readlines(), will return all lines received within the specified time out.
- The size argument is ignored.
- Consider the same string used in readline()rnSerial Uploadrn
Closing the Serial Port
After finishing read and write operation. We have to prperlyclose the serial port.
Concluding Notes
Hope this article will help you to kick start using serial API to testyour devices which is using serial port.