PROPOSAL AND EVALUATION OF TIME-CRITICAL COMMUNICATION PROTOCOL ON LAN

In the field of control and communication using LAN, such as plant con trol, there exists a requirement for the time critical property that t he data transfer should be completed in the specified time (time windo w), in addition to the requirement for the high speed. In the timed to ken protocol (TTP) that has been used in FDDI and other systems, howev er, the transfer time increases when the input traffic exceeds the sys tem specification, making it impossible to maintain the time-critical property. This paper proposes an extension of TTP where only the data that can be transferred within the time window are allowed to transver se by applying dynamic distributed management to the data transmission queue in each node. To demonstrate the performance of the proposed pr otocol, simulations are executed under various conditions; and it is v erified that the protocol is effective when applied to the time-critic al communication.