+---------+                         +-----------+
 |       Tx|---------+-------------->|Rx         |
 | Master  |         |               | Controller|
 |       Rx|<--------------+---------|Tx         |
 +---------+         |     |         +-----------+  
                  +--V-----V--+                   
                  | Rx1   Rx2 |                   
                  | "sniffer" |                    
                  |           |                   
                  +-----------+