| 摘要 |
PURPOSE:To execute the test of a line connection circuit in a faulty state without giving affect on the operation of other normal lines by providing a disconnection means disconnecting each of line connection circuits from a line control section. CONSTITUTION:The line control section 10 controls line connection circuits 20a-20n to apply normal data transmission/reception. If a fault takes place at a line connection circuit 20m, a loopback test executing signal is outputted to the interface circuit 34 of a test control section 30. A switching signal of the faulty line connection circuit 20m is outputted to a switch control section 50 based on the line address from an address management section from the interface circuit 34 and the switch control section 50 applies the changeover of a switch section 60 and the internal logic loopback of the line connection circuit 20m. If an error is detected by the test, its detailed data is stored in a RAM 33, it is informed to the line control section 10 via the interface circuit 34 and reported to a host equipment 3.
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