| 摘要 |
PURPOSE:To decrease the number of parts by transmitting the start signal from a master device in a prescribed cycle and therefore eliminating the need to add an address code to each telephone set. CONSTITUTION:The multiple connection is secured via a common signal line LS between a main device KSU and telephone sets ST1-ST4 respectively. At the same time, these telephone sets are connected individually to the device KSU via private lines L1-L4. Then start signal transmission circuits SS1-SS4 provided within the device KSU transmit start signals successively with superposition to the lines L1-L4 in a prescribed cycle respectively. While each of the ST1-ST4 performs transmission of signals to the device KSU by a transmission circuit SC and a reception circuit RC in the device KSU in response to the detection of the start signal. In such a way, the addition of an address code is eliminated to each telephone set. This can reduce the number of component parts. |
