Problem running simulation in external mode in Matlab Simulink

Hello.

I use Matlab 2013b with Arduino support package and library in Simulink.

Yesterday I got new Arduino Mega 2560. I installed drivers, Arduino software, everything was fine. I installed support package for Simulink, run few demos, even used it in 'external' mode for real-time data aquisition for my model in Simulink, everything was working fine.

Today I wanted to continue my work, so I tried to run projects from yesterday. I am able deploy my code to Arduino board without any problems and it is working fine on it. However, when I try to start the simulation in 'external' mode to get real-time readings in Simulink, it gives me following error:

External mode simulation is not supported for the 'Arduino Mega 2560' hardware. However, you can deploy the model on this hardware. From the model window, click the "Deploy to Hardware" button.

Ekhm, I'm confused. I had absolutely no problems running it yesterday, but now it gives me this kind of error..? I believe settings are correct, I didn't even change enything from when it was working okay.

I am completely new to Arduino, so it might be some kind of dumb problem, but I didn't find any solutins to this in google.

Can you help me?

Can you help me?

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