COMMUNICATION CONTROLLER USING HDLC PROTOCOL

摘要

PURPOSE:To prevent a busy state by informing production of a fault to a host layer processing and untransmitted data, and stopping a data transmission request from a host layer processing when a fault of disabling data transmission in the link layer processing is detected. CONSTITUTION:If a fault disabling communication between stations A and B takes place, when a link layer processing 1a2 of a station A detects line interruption through a physical layer 1a1, the data transmission to a station B is stopped and the occurrence of a fault is informed to a host layer processing 1a3. The content of notice includes transmission data 4, 5, 6 having the presence of the transmission request from the host layer processing 1a3 but have been not sent and the host layer processing 1a3 stops the further data transmission request and stores the data 4-6 for retransmission. Thus, the resident data in the link layer processing is eliminated to prevent a busy system.