Non blocking UDP receiver in Matlab GUI - matlab

Question

I'm creating a MATLAB GUI using the app designer (very similar to, but better than, GUIDE) which I want to use to monitor the data output of my simulink model in real time.
In other words, I have a simulink model and a GUI, both running in the same MATLAB instance and I want to send packets over UDP from the simulink model and use that data in my GUI to update plots. However, I don't know how to read the data from the UDP packet without blocking.
Is there a way to bind a handler when a packet is received so that I can execute a function to update plots/fields?

Answer 1

Of course, beside BytesAvailableFcn matlab has the datagramreceivedfcn to call your custom function on new dagatrams, which is nonblocking while fread/fscanf are blocking (temporarily). Regarding callbacks in matlab read events and cbs
Compilable standalone could look like:
%% standalone main
%{
see docs/*
%}
function exitcode = main(port, remotePort)
% sanitize input
if(~exist('port','var') || ~exist('remotePort','var'))
disp(['args: port remotePort']);
exit(1);
end
if ischar(port)
port=str2num(port);
end
if ischar(remotePort)
remotePort=str2num(remotePort);
end
% create udp object
u = udp('127.0.0.1',remotePort, 'LocalPort', port);
% connect the UDP object to the host
fopen(u);
exitcode = 0;
% since we poll, suppress warning
warning('off','instrument:fscanf:unsuccessfulRead');
warning VERBOSE
% specify callback on datagram
while true
msgEnc= fscanf(u);
% timed out without datagram
if isempty(msgEnc)
continue
end
% do sth with msgEnc (which is a readable string)
fprintf(u, 'heard sth'); %answer
end
end
If you would like to use simulink block use udpreceive
which has a non-blokcking capability
A First In First Out (FIFO) buffer receives the data. At every time
step, the Data port outputs the requested values from the buffer. In a
nonblocking mode, the Status port indicates if the block has received
new data.