| 摘要 |
PURPOSE:To perform the data communication between a compact and light- weight data storing device and a data output device via a small number of signal lines, by holding a data transmitting signal line at a logical level opposite to a waiting mode for request of data transmission when the transmission of data is over. CONSTITUTION:The waveform of a data transmission request clock signal sent from a data collector is shown by (A), and a data transmission request clock RC of a prescribed cycle is consecutively transmitted after a data transmission request mark RM. While a transmission data signal waveform obtained from a vending machine is shown by (B). A data signal line is set at a high level when the clock RC is changed to a low level L from a high level H. Thus a high logical level ''1'' is shown for a data pulse TD. In the same way, the data signal line is set at a low level when the clock RC is changed to a level L from a level H. Thus a low logical level ''0'' is shown for the pulse TD. Then the data signal line is held at a high level when the transmission is through with a prescribed number of bits, and a data transmission end signal is transmitted. |
