| 摘要 |
PURPOSE:To delay a polling period to a non-response device at random, by providing a counter to which each different numerical value can be set, on plural devices, and driving the counter at every polling cycle. CONSTITUTION:When polling is executed from a control device 1, unless a value of a timing counter 22i of a corresponding device 2i is ''0'', it is shifted to the next device by subtracting 1 from its value, and when the value of the timing counter 22i is ''0'', the polling operation is executed. In case there is no answer in response to this polling, a value of a period counter 21 in the control device 1 is set to the timing counter 22i, and only ''1'' is added to the period counter. Subsequently, said operation is executed in order to each device 2(21-2n), and when it ends as to all the devices, the maximum value of the timing counter 22i is set to the period counter 21, and it is shifted to the next polling cycle. |
