local digital ioopback towards the local user dte. the ioopback is performed by connecting the el digital transmit signal to the input of the receive path, without passing through the main link interface. signal paths are shown in figure 5-3. the test signal is provided by the local dte that must receive its own transmission. the test checks the digital circuits of the local fcd-2 (dsu) and the connections to the local dte.

    the test ioopback can be activated only when the internal dbg jumper is set to on (see section 2.4 for details).