| 摘要 |
PURPOSE:To prevent system-down even when no terminal exists corresponding to an accessed address or the terminal device is faulty by sending each bit data of a control data to a terminal device to be accessed sequentially while reception acknowledgment is executed only when an address coincident signal is returned. CONSTITUTION:A reception signal is discriminated by a reception signal discriminating section 21 only when an address data AD of a transmission data Dn is discriminated for the coincidence with the own specific address and an address coincident output is obtained. When the address coincident signal AGR is received, each bit data of the control data CD is sent sequentially to a terminal device 2 corresponding to the accessed addresses (n), (l), (k) while the transmission is confirmed by using a reception acknowledgment signal ACK. Further, no control data CD is sent to an address (m) to which no address coincident signal AGR is returned while it is discriminated that no terminal device 2 exists or it is faulty, and the address data AD to access the next address 1 is sent to the control data CD to the terminal device 2 having the address 1.
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