| 摘要 |
PURPOSE:To perform rationally the processing control when a line is busy, by performing the check whether or not monitor information is transmitted correctly, retransmission and alarming and the like, when transmitting the monitor information to a monitor station with the use of a telephone exchange line network. CONSTITUTION:The alarm display is performed if no response is obtained regardless of repetitive calling of a master station, in transmitting the monitor information of a slave station to the master station via a telephone line. The line is released, when the master station responds but no information transmission request signal ENQ exists, that is, in case of misdialing. A slave station receiving the ENQ signal transmits the monitor information repetitively for plural number of times. The master station transmits an ACK signal when the information is confirmed and an NAK signal when the information is received incompletely. The slave station releases the line acquisition when the ACK signal is received and performs retransmission when the NAK signal is received. When the number of retransmissions exceeds a prescribed number of times, the line acquisition is released once and the line is caught again after a prescribed time for the retransmission of the information. When the release of the line and reacquisition exceed a prescribed number of times, the line acquisition is stopped and the alarm display is performed. |
