Python Module for Sending & Receiving UDP in MATLAB

Overview

This Python module provides functions to send and receive UDP messages in MATLAB (or directly in Python).

MATLAB functionality assumes you have MATLAB set up to run Python code. See: https://www.mathworks.com/help/matlab/call-python-libraries.html

In the examples below, replace my IP address (192.168.1.12) with your IP address.

Files:

• matlab_udp.py contains the module. No other files needed to use the module.
• udp_send.py is a Python script that uses the module to send a UDP message in Python or terminal command line.
• udp_rx.py is a Python script that uses the module to receive a UDP message in Python or terminal command line.

Sending UDP with matlab_udp Module

Use the module's send() function to send a message via UDP to a specified IP and port.

The function returns the number of bytes sent.

Example usage in MATLAB:

>> a = py.matlab_udp.send('192.168.1.12', 5005, 'Hello');

Example usage in Python:

>>> import matlab_udp
>>> matlab_udp.send('192.168.1.12', 5005, "Hello")

This message can be received in Linux using netcat to listen:

$ nc -kluv 5005
Listening on [0.0.0.0] (family 0, port 5005)
Hello

Receiving UDP with matlab_udp Module

Use the module's receive() function to receive a message via UDP from a specified port.

The function will block until a UDP message is received.

The function returns the message, IP address of sender, and port of sender.

Example usage in MATLAB:

>> msg = py.matlab_udp.receive(5005);

Then, send a message from a Linux terminal using:

$ nc -u 192.168.1.12 5005
Hello

The msg variable contains the message:

>> msg
msg = 
      Python tuple with no properties.
    ('Hello\n', '192.168.1.12', 47185.0)
>> char(msg{1})
ans =
    'Hello
     '
>> char(msg{1}(1:end-1))
ans =
    'Hello'
>> char(msg{2})
ans =
    '192.168.1.12'
>> msg{3}
ans =
       47185    

Note that nc sends an end-of-line, so the message string has an end-of-line. This module's send() function does not send the end-of-line.

Example usage in Python:

>>> import matlab_udp
>>> matlab_udp.receive(5005)

Then, send a message using:

$ nc -u 192.168.1.12 5005
Hello

Python will show:

(u'Hello\n', '192.168.1.12', 47185.0)

Running from Linux Command Line

To send a message via UDP from a Linux terminal using the matlab_udp module, use the udp_send.py script.

$ python udp_send.py 192.168.1.12 5005 "Hello"
Sent 5 UDP bytes to 192.168.1.12:5005  Hello

This message can be received in another Linux terminal using:

$ nc -kluv 5005
Listening on [0.0.0.0] (family 0, port 5005)
Hello

To receive a message via UDP from a Linux terminal using the matlab_udp module, use the udp_rx.py script.

$ python udp_rx.py 5005

Then, send a message from another Linux terminal using:

$ nc -u 192.168.1.12 5005
Hello

The terminal running udp_rx.py will show:

Received UDP from 192.168.1.12:47185 Hello