digraph overview {
	subgraph cluster0 {
		label = "Main System";
		fontname=Arial;
		fontsize=20;
		node [style=filled,color=white,fontname=Arial];
		style=filled;
                color=lightblue;
		l1 -> Server -> r1;
		l2 -> Server -> r2;
		r1 -> Server;
		r2 -> Server;
		l1 [label = "Light Meter 1"];
		l2 [label = "Light Meter 2"];
		r1 [label = "Relay 1"];
		r2 [label = "Relay 2"];
	}
	e -> Server;
	Server -> e;
	e [label = "Eyes and Ears",fontname=Arial;];
}