Initializing a serial object in one simulink block, retrieving it in another

I have serial comm. up and running between matlab and an arduino in order to interface with an RC transmitter via a PPM signal. I use a function to initialize the channel, then another function to transmit on that channel. How can I accomplish this in simulink? It would be ideal to have a block that ran once, or that I could click to init. I'll also need to know how best to retrieve the serial object in the 'transmit' block.