| 摘要 |
PURPOSE:To eliminate the institution of a test signal receiving and transmitting circuits on all signal converting interface parts by providing a common test signal outgoing circuit and a common test receiving circuit at a loop back test circuit. CONSTITUTION:When a signal converting circuit 12 of a signal converting interface part 2 for the external signal of an attribute A is tested, a common test signal outgoing circuit 14 of the loop back test circuit 1 is excited, a common test signal is generated, and the test signal of the attribute A is generated at a test signal outgoing circuit 6 of the interface part 2. The test signal of the attribute A is communicated to the circuit 12, converted, inverted, folded, and a test result is decided at a test receiving circuit 9, and when the result is normal, a gate circuit 16 is opened. The common test signal sent to a multiple bus 4 is loop-backed at a circuit 16 and returned to a multiple bus 5, only when the test result is normal. The signal is received at a common test receiving circuit 15, and the normally of the circuit 12 is detected. |
