| 摘要 |
PURPOSE:To prevent a vacant polling and to reduce ineffective interruption, by utilizing a CPU which makes polling to each terminal polling data exists sequentially and automatically and accomplishes the polling only when no polling exists at all terminals. CONSTITUTION:A CPU2 discriminate if a polling start command is given and when given, a communication control unit (CCU)8 discriminates if terminal devices 15a-30h have polling data. If the terminal devices 15a-30h have the polling data, the data is transmitted from the terminal device to the CPU2 and generates the interruption of presence of the polling data. If no polling data exists in the terminal devices 15a-30h, all the terminal devices 15a- 30h are subjected to polling and the interruption of absence of polling data is generated to the CPU2 when polling of the terminal devices 15a-30h is accomplished. |
