MATLAB: Error while connecting to realtime target

Question

Hi, I made level 2 s-function in C language, which sends some data via serial port. I compiled it with Microsoft Visual C++ 2008 SP1 compiler. When I add this s-function to simulink model and start the simulation in normal mode, everything is ok, but, when I want to connect with realtime target (after building with rtwin.tlc), I get this error message:

Error occurred while executing External Mode MEX-file 'rtwinext': Error loading real-time executable: undefined symbol "_InterlockedExchangeAdd"

I have not any idea, what this error means. Could anybody help me? Thanks.

Answer 1

For serial port communication, please use Packet Output or Stream Output blocks, depending on your data format. You are correct that you cannot use Windows API in real-time code.