digraph G {
   node [shape=plaintext fontsize=12];
   graph [rankdir=LR];

   subgraph cluster_0 {
        node [shape=box];
        label="PTY"
        "Master" -> "Slave" [dir=both arrowsize=.5];
    }

   "ACRN-DM" -> "Master" [arrowsize=.5];
   "Slave" -> "User VM:/dev/ttyS1" [arrowsize=.5];

}