Patent ID: 8126008

Claim:
A communication system comprising a plurality of communication apparatuses that communicate with each other during a cycle in a time division mode, wherein the cycle includes: a plurality of data communication sub-slots respectively allocated to the plurality of the communication apparatuses for data communication; and a maintenance communication sub-slot used for maintenance communication of the plurality of the communication apparatuses, wherein each of the plurality of the communication apparatuses comprises: a communication setting register having set thereon setting values related to the cycle in the time division mode, a data communication sub-slot allocated to the respective communication apparatus, and the maintenance communication sub-slot; and a communication controlling unit that controls communication in the time division mode based on the setting values set in the communication setting register to transmit a first data frame including data to be transmitted in the data communication sub-slot allocated to the respective communication apparatus, the communication controlling unit using data included in a second data frame received in a data communication sub-slot allocated to another communication apparatus to control the respective communication apparatus, wherein one of the communication apparatuses operates as a master communication apparatus and communication apparatuses other than the master communication apparatus operate as slave communication apparatuses, the master communication apparatus further comprising: a configuration register having registered thereon setting/monitoring information related to the maintenance communication, wherein the communication control unit of the master communication apparatus transmits, in the maintenance communication sub-slot, a maintenance frame to change or monitor the setting values set in communication setting registers of other communication apparatuses based on the setting/monitoring information registered in the configuration register, wherein a communication control unit of at least one of the slave communication apparatuses transmits to the master communication apparatus or sets, in the maintenance communication sub-slot, at least some setting values of the communication register in response to a received maintenance frame addressed to the slave communication apparatus.