Looped transmission line re-built system

摘要

PURPOSE:To enable the monitor of loop back at a normal time for a loop monitoring device and to release the loop back without stopping the operation of a loop even when a fault is generated by providing a means to make an inquirement to each data transmission equipment, means to return a signal, means to release the loop back and means to send a signal to the loop monitoring device. CONSTITUTION:When the recovery signal of a fault data transmission equipment 10 is received, a data transmission equipment 10 inquires the propriety to release the loop back to a loop monitoring device 3 by using the inquiring means. When a time is within a loop back holding time, the loop monitoring device 3 sends a response signal, which shows impossibility to release the loop back, by using the sending means to the output of the inquiring means and when the time exceeds the loop back holding time, the response signal is returned to show the possibility by release the loop back. When the returned signal showing the possibility of the release is received by the returning means to the output of the inquiring means of after the lapse of a prescribed time in the loop back holding time, the response signal to show the possibility of recovery is returned. Then, after it is confirmed that the response signal is normally received, the loop back is released by the releasing means.