Patent ID: 8224182

Claim:
A switch device, comprising: transmission/reception unit each connected to each of apparatuses through a communication cable for transmitting/receiving a signal to/from each apparatus; a connection switching unit for switching connection between said apparatuses by switching connection between said transmission/reception unit; a reception state monitoring unit for monitoring a signal reception state of said transmission/reception unit; and a transmission stopping unit for executing signal transmission stopping processing according to a monitoring result obtained by said reception state monitoring unit with respect to other said transmission/reception unit to which connected through said communication cable is another apparatus having a connection relationship with said apparatus to which said transmission/reception unit is connected through said communication cable; wherein said communication cable is an optical transmission cable, and said transmission/reception unit is a photoelectric transducer for converting an optical signal communicated with said apparatus through said optical transmission cable into an electric signal, said reception state monitoring unit comprises a quantity of light monitoring unit for monitoring a quantity of received light of said photoelectric transducer, and said transmission stopping unit comprises a quantity of light eliminating unit for eliminating a quantity of transmission light of other photoelectric transducer as said other transmission/reception unit, wherein said quantity of light eliminating unit, according to a monitoring result obtained by said quantity of light monitoring unit, when a quantity of received light of all said photoelectric transducers to which connected through said optical transmission cable are all apparatuses having a connection relationship with specific said apparatus attains 0 based on connection path information indicative of a connection relationship set in advance between said apparatuses, eliminates a quantity of transmission light of said other photoelectric transducer to which said specific apparatus is connected through said optical transmission cable.