| 摘要 |
PURPOSE:To shorten a communication time as less as possible by transmitting again the data sent to a receiver from a transmitter in case an invalid answer or no answer is given to said data from the receiver within the set reference time. CONSTITUTION:A signal ENQ is sent to a receiver R from a transmitter S to set up a data link, and the data link is set up when the answer reception ACK is given from the receiver R. In case a negative answer NAK is produced due to the noise, etc. of communication, the transmission of the ENQ is repeated up to the set (i) times. Then the answers NAK are outputted continuously to the (i+ 1)th transmission. In such a case, a system fault is decided and the communication is discontinued. While the ENQ is transmitted repetitively until the answer ACK is delivered within the prescribed reference time in case an invalid answer or a negative answer is outputted to the ENQ. When no valid answer nor no other answer is outputted even after the reference time is over, a system fault is decided to discontinue the transmission. In such a way, a data link is set up also in case an invalid answer or no answer is supplied during transmission of other data. |
