How to transmit CAN messages only if there is a change

Hi everyone,

I have multiple controller connected to my simulink model through a CAN bus.

Right now I send all the messages at each step time, like the one which controlls the controlle mode, etc,which normally do not change that much,may be once or twice throughout the simulation. But I send them anyway which apparantly cause CAN bus to be oerloaded.

I wonder how I 'll be able to send command only if there is a change in values?