digraph overview {
	node [fontname = Arial];
	subgraph cluster0 {
		style = filled;
		color = lightgrey;
		l1;
		l2;
	}
	l1 -> server;
	l2 -> server;
	server -> r1;
	server -> r2;
	r1 -> server;
	r2 -> server;
	l1 [label = "Light Meter 1", color = lightblue, style = filled];
	l2 [label = "Light Meter 2", color = orange, style = filled];
	r1 [label = "Relay 1", color = lightblue, style = filled];
	r2 [label = "Relay 2", color = orange, style = filled ];
	server [label = "Midpoint (Server)"];
}