| 摘要 |
PURPOSE:To improve the transmission efficiency without using a control code identifying the transmission between the primary station and the secondary station and without using an address for the data from the secondary station by allowing the primary station and the secondary station to modulate sending data with different data length respectively and send the modulated data onto a transmission line. CONSTITUTION:The primary station 1 modulating an address and a data signal in succession to the address and sending the modulated data to connected secondary stations 2-4, and the secondary stations connected to the primary station of multi-drop type, demodulating the data signal when a modulation signal is obtained on a transmission line 6, receiving the signal when the address is coincident with its own address and sending the data to the primary station are connected, the data sent from the other secondary station and the data sent from the primary station are identified depending on the presence of the modulation signal of the prescribed data length to apply the data transmission to the primary station. Thus, when lots of secondary stations are connected to the primary station, the data is transmitted in a short time without using the control code identifying the transmission between the primary station and the secondary stations and without using an address for the data from the secondary station.
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