With CMS installation nearing completion, the three levels of the final read-out system of the Drift Tube (DT) chambers are presented. First, are the Read Out Boards (ROB), responsible for time digitization of the signals generated by a charged particle track. Second, the Read Out Server (ROS) boards receive data from 25 ROB channels through a 240-Mbps copper link and perform data merging for further transmission through a 800 Mbps optical link. Finally, the Detector Dependent Units (DDU) merge data from 12 ROS to build an event fragment and send it to the global CMS DAQ through an S-LINK64 output at 320 MBps. DDUs also receive synchronization commands from the TTC system (Timing, Trigger, and Control), perform error detection on data, and send a fast feedback to the TTS (Trigger Throttling System). Functionality of these electronics has been validated in the laboratory and in several test-beams, including an exercise integrated with a fraction of the whole CMS detector and electronics that demonstrated proper operation and integration within the final CMS framework
