| 摘要 |
PROBLEM TO BE SOLVED: To restrict the number of communication devices to be connected so that a power capacity capable of receiving from an external power supply may not exceed its level when a plurality of communication devices are connected and they share the external power supply. SOLUTION: When an external AC power supply is shared by a plurality of I/O boxes 30, four input and four output terminals of each power supply connector 41 of the I/O boxes 30 are provided corresponding to the number of devices possible to be connected (five connectors in this case). The external AC power supply is shared by from the first to the fifth I/O boxes 30, and power is not supplied from the power supply connector 41 of the fifth I/O box 30 to the I/O boxes 30 connected to a device of the next stage (the sixth device, exceeding the number possible to be connected). COPYRIGHT: (C)2003,JPO
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