Simulink does not support unions. However, you can work around this by treating the union as a Simulink.Bus data object with DataScope of "Imported" and Header file is the name of the hand-written header file defining the structs and unions. https://www.mathworks.com/help/simulink/slref/simulink.bus.html# This approach treats each field of the union as different memory locations during simulation and therefore is only valid if the SImulink model reads and writes to just one of the union fields. If you attempt to write to one union field and then read from another, you will not get the expected result during simulation.
Hope this helps
Mark.
