| 摘要 |
PROBLEM TO BE SOLVED: To detect the position relation of a slave and a repeater, etc., connected to a network in a field network of bus type. SOLUTION: A master unit 11 and a measurement tool apparatus 60 send a command to selected two node stations #1 and #2 and measure the time t1, t2, s1 and s2 taken until the return of a response. Obtained measured values are substituted to y=(t1-t2)-(s1-s2), and it is determined that the node station #1 is positioned on the master unit side when the value of y is negative and that the node station #2 is on the master unit side when it is positive. Even while the respective node stations have the internal processing time intrinsic to a communication IC and it is individually different, since the subtraction processing of the measured values takes place for the same node station like t1-s1 and -t2-(-s2) in the determination equation, the internal processing time is offset, the value of y corresponds to a distance, and the position relation is accurately specified. COPYRIGHT: (C)2009,JPO&INPIT
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