| 摘要 |
PURPOSE:To reduce the number of communication lines, by detecting the nobusy state of the other equipment by one equipment to transmit data from one equipment and by detecting data transfer from the other equipment by one equipment to receive transfer data, in the system simultaneous two-way data transfer is not required. CONSTITUTION:When equipment A transmits data to equipment B, equipment A detects whether input signal AI from communication line W is high-level or not, and equipment A waits until signal AI becomes high-level if signal AI is low-level, that is, equipment B is busy. When signal AI becomes high-level, equipment A transmits output signal AO through transistor inverter 5, and this signal is received as input signal BI of equipment B. Equipment B decides whether signal AO is the data transmission request to equipment B or not after the delay time after receiving of signal AO; and if it is the transmission request, output signal BO is transmitted from output terminal 4 of equipment B through inverter 6; and if it is not the transmission request, output terminal 4 is made high-potential to indicate that equipment B is busy, and output terminal 4 is made low-potential after the processing in equipment B. |
