UDP connection in two instances of Matlab

Hi, I'm trying to sendi information between 2 instances of Matlab running at the same time. I've been able to use UDP in the past, but this doesn't seem to work.

% I would be sending info through instance A (integers with varying sizes each time, but only one integer at a time)
  u = udp('192.168.1.1', 2011, 'LocalPort', 2012);
    fopen(u);
   
    data = 1000;
    
     fwrite(u, data);

And then waiting for the data to arrive using another instance of matlab:

    % and receive data on instance B
     
     u = udp('192.168.1.1', 2012, 'LocalPort', 2011);
    fopen(u);   
 
    signal = [];
    
    while isempty(signal) == 1 % pooling until signal is received
        
        signal = fscanf(u,'%d');        
        
    end

What am I missing?

I would also ideally need to send a message from the first instance to be read by the second instance later.

So Instace A would give me the number I need and send it as soon as it gets it. Meanwhile, instance B might be doing another operation and not able to receive the data instantly, but with a delay.

I have already made sure the ports are not block by the windows firewall udp tcp/ip connection.

How can we do that?

Thanks!

Answer 1

[Walter Roberson]

You are fwrite() of the data, which writes binary. You are fscanf() of the data, which expects text.

fprintf(u, '%d\n', data);

[Mateo Leganes Fonteneau]

Thanks, but that doesn't seem to fix it. I've tried it in 2 different machines, and fscanf is not receiving anything.

[Walter Roberson]

Tested code attached.

Note: this is for use talking from a system to itself.

[Mateo Leganes Fonteneau]

Thank you. Indeed, the remote host was the problem after fixing fprintf.

Seeting RemoteHost to '127.0.0.1' works for UDP. Remotehost as '192.168.1.1' was working for TCP/IP but not for UDP.