| 摘要 |
PROBLEM TO BE SOLVED: To always set optimum polling start between master and slave stations for each slave station and to operate it by providing a polling table consisting of a priority table which records a slave station number that undergoes priority connection and a normal table which records a slave station number that does not undergo priority connection. SOLUTION: A polling table 12 is provided with a memory which stores a priority table 121, a priority table counter 122, a normal table 123 and a normal table counter 124. When transmission request confirmation from a master station to a slave station arises, a transmission processing part 14 processes a transmission request confirmation signal. And, when the priority of a response from the slave station to the transmission request confirmation is high, a corresponding slave station number in the table 12 is subjected to registration exchange from the table 123 to the table 121. On the other hand, when a response is slow and a priority is low, registration is switched to the table 123 when the corresponding slave station number is registered in the table 121 in the table 12.
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