The way you have it, use a controlled source connected to the widing (control) and apply the correct voltage/current to activate the relay. You can connect a simulink step block to an s->ps converter to send a signal to the controlled source. Set the step magnitude to the correct value to turn on the switch. The voltage source you have attatched is set to 0V, so it is not activating the switch. Also, your circuit is all open circuits so the voltages will always measure 10 V as the whole switch is raised 10V by the other dc source. You should add resistors to ground at the S1 and S2 ports. This will pull them down to ground unless they are actually connected to the 10V source through the switch.