Communication system, communication device and communication method

A communication device network-connected to a communication system including a time master that includes a master clock that manages time of the communication system,

• the communication device comprising:
• a slave clock that is time-synchronized with the master clock;
• a synchronization module that performs time synchronization with a first communication device connected adjacent to the communication device at a master side on the network;
• and
• a communication module that notifies the time master of time synchronization information that indicates time synchronization accuracy of the communication device obtained by the synchronization module,
• wherein
• the synchronization module corrects time of the communication device by using a difference between time of the first communication device and the time of the communication device as a time adjustment value, and
• the communication module notifies the time master of the time adjustment value as the time synchronization information.

A communication method in a communication system in which a plurality of communication devices are connected to a network, the plurality of communication devices including:

• a time master including a master clock that manages time of the communication system;
• and
• a plurality of time slaves each of which includes a slave clock that is time-synchronized with the master clock,
• the communication method comprising:
• time-synchronizing each time slave of the plurality of time slaves with a first communication device connected adjacent to the each time slave at a master side on the network;
• and
• notifying the time master of time synchronization information that indicates time synchronization accuracy of the each time slave,
• wherein
• the time-synchronizing includes correcting time of the each time slave by using a difference between time of the first communication device and the time of the each time slave as a time adjustment value, and
• the notifying the time master includes notifying the time master of the time adjustment value of the each time slave as the time synchronization information.