| 摘要 |
PROBLEM TO BE SOLVED: To transmit a data signal at a high speed even when the number of expansion units is increased. SOLUTION: Disclosed is a communication method which performs: the transfer processing of data signals S1 ... from a PLC body 10 to a plurality of expansion units 21 to 24 synchronously with clock signals CLK1 ... between the PLC body 10 and the plurality of expansion units 21 to 24 successively connected via communication cables 31 to 34 with the PLC body and connected between the expansion units; and capturing processing of those data signals to be returned to the PLC body 10 side after the completion of transfer. This communication method includes steps of: transferring the data signals from the PLC body synchronously with the clock signals; making data signal processing signals P1 ... having the same cycle as that of the clock signals rise after the lapse of the delay time of the data signals caused by the passage of the communication cables and the expansion units since the start time of the transfer of the data signals; and performing the capturing processing of the data signals according to the data signal processing signals which are made to rise with the above cycle after the lapse of the above delay time. COPYRIGHT: (C)2011,JPO&INPIT
|
