| 摘要 |
PURPOSE:To easily specify a faulty maintenance unit in a shift path by by-passing at least one of shift registers as plural maintenance replacement units constituting the shift path to perform trouble diagnosis. CONSTITUTION:If trouble in shift registers 1-3 is detected, an output control circuit 12 outputs an error report signal 112 to a maintenance diagnosing device 13. This device 13 outputs a control signal 116 to an input/output control circuit 15 and instructs one of shift registers 1-3 to change the input/output connection. If the connection change instruction is first issued to the register 1, the control circuit 15 instructs a connecting circuit 16 to change the connection to the register 1 by a control signal 118. After a shift register designating circuit 6 and a shift mode designating circuit 4 are controlled by the control signal 118, scan-in and scan-out operations are performed. |
