Check out the VBA part of Excel, on the computer where PLCSIM is installed the VB Object list should show a "Prosim" activeX control. This control gives VB and VBA enabled applications access to the PLCSIM resources. Check the PLCSIM documentation for a manual. Otherwise any communication tool or HMI, like the SIMATIC Data Control that comes with WinAC, can access the PLCSIM through the MPI Interface, if PLCSIM is started it reroutes this interface to itself
