| 摘要 |
PURPOSE:To reduce data collecting time, by performing inquiry of information only to slave stations having information to be transmitted to a central control station. CONSTITUTION:A central control station 1 transmits an information presence/ absence retrieving code Code 1 inquiring the presence/absence of the information to all slave stations 4-7 via common line 2. When the slave station 7 receives a retrieval code, if the information to be transmitted of the station of itself is presented, a bit is set to a frame E and a Code 2 is transmitted to the slave station 6. On the other hand, after the slave station 6 receives the Code 1, the station waits for a response signal from the slave station 7, and the station 6 receives said Code 2, then a bit is set to a frame D and gives signals to the slave station 5 in the form of a Code 3. Similarly, the information presence/ absence retrieving code is transferred from the slave station 5 to the slave station 4 and from the slave station 4 to the control station 1. On the other hand, the control station 1 can discriminate the transmission request of the slave stations by checking the bit in the frames and transmits a transmission permitting code Code 6 only to the slave station 6 making the transmission request. |
