In some examples, an optical time-domain reflectometer (OTDR) device may include a laser source to emit a laser beam into a device under test (DUT), and a connection port to connect the OTDR device to a first end of the DUT, where the OTDR device may be designated a first OTDR device. A sensor display generator may determine a length of the DUT, receive, from a second OTDR device connectable to a second opposite end of the DUT, and over the DUT, OTDR information acquired by the second OTDR device in a direction from the second OTDR device towards the first OTDR device, and ascertain, based on acquisition by the first OTDR device, further OTDR information in a direction from the first OTDR device towards the second OTDR device. The sensor display generator may generate a bi-directional combined schematic display that includes relevant optical events with respect to the DUT.