You can do this using the set_param function. I have attached an example Simulink model and script you can run to demonstrate this. For simplicity I set the value using a loop with a pause. This will block you from doing anything else on the command line while it is running. I would suggest that you implement similar logic using a timer if you want to continue to use the command line while the simulation runs. If you don't know how to do this please let me know and I can give you an example.
% Increment value in Simulink using loop with pause
Tupdate = 1; % update period [s]
blockName = 'SetExternalExample/Constant' %constant block whose value is to be changed
% Start infinite loop to update value
% you will have to ctrl-c to break out of this loop
keepRunning = true;
count = 0;
while keepRunning
% Change block value to current count
set_param(blockName,'Value',num2str(count))
pause(Tupdate)
% Increment counter
count = count + 1;
end
I don't think that @Guillaume's approach will work, as Simulink doesn't read from the workspace once the simulation has started running.
