| 摘要 |
PROBLEM TO BE SOLVED: To provide a unit extension system capable of individually accessing a plurality of extension units without setting a code number for each extension unit. SOLUTION: A plurality of extension units 2 is connected to a main unit 1 in chain-like fashion via a signal line Ls. The signal line Ls includes a basic signal line L0 used to transmit an instruction and a response between the main unit 1 and the extension units 2, and a control line L1 requesting the extension units 2 to receive an instruction. The extension unit 2 includes a first connecting section 23 connecting the signal line Ls on the side close to the main unit 1, a second connecting section 24 connecting the signal line Ls on the side far from the main unit 1, and a signal processing section 20 that enables the reception of an instruction when the control line L1 of the first connecting section 23 becomes active. If a received instruction is a unit transition instruction, the signal processing section 20 activates the control line L1 of the second connecting section 24 and disables the reception of an instruction. COPYRIGHT: (C)2008,JPO&INPIT
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