| 摘要 |
PURPOSE:To facilitate an easy discrimination for a fault point, by installing a test pattern detecting circuit between the switch parts of an inward trunk and storing an input/output interface part into a digital switch network to form a loop-shaped channel. CONSTITUTION:The two contrary test patterns are transmitted from a test pattern producing circuit 3 in an optional time slot to be detected by test pattern detecting circuits 4a-4c provided among switch parts 5b-5d that form a channel of an inward trunk 2. At the same time, the input/output interface parts 5a and 5e are stored in a digital switch network 6 to form a loop-shaped channel. Thus a component parts having a fault can be discriminated from the decision of the circuits 4a-4c. |
