COMMUNICATION DEVICE, SYNCHRONIZED COMMUNICATION SYSTEM, AND SYNCHRONIZED COMMUNICATION METHOD

摘要

A communication device and method are provided in which even when communication devices are connected in series to a transmission path, devices connected to the individual communication devices are synchronized so that a communication cycle can be reduced. A second communication device (2) includes a relay path (260) and a return path (261) which do not pass through a storage device, and a path selection switch (250) therefor. A first communication device (1) instructs switching of the return path (261) from a transmission path (5), measures a transmission path delay time, notifies the second communication device (2) of it, and sends a reference time of the first communication device for each communication cycle. The second communication device corrects its reference time using the transmission path delay time and the reference time. Also when a new second communication device (2) is found during synchronized communication, the first communication device (1) performs transmission path delay measurement using the remaining time in the communication cycle. Furthermore, the first communication device and the second communication device include means for detecting a frame start signal and reducing transfer delay.