| 摘要 |
A method for polling a plurality of remote communication devices (RTUs), each of which has an active response state and an inactive sleep state, comprises transmitting a wake-up message (T1-T3 and T'2), from a control centre, to the plurality of remote devices, each of which, in response, enters its active response state. The control centre sequentially polls each active remote device and, at the termination of a "wake-time" period of time and after the completion of the polling sequence, the remote devices return to their inactive sleep states. The length of the wake-time is specified in the wake-up message. Different groups of devices may receive respective different wake-up messages with different wake-times. <IMAGE> |
