| 摘要 |
PURPOSE:To form a subscriber system having the same terminal whether or not a subscriber line is a single subscriber line or a branch circuit, by performing the link control of the terminal accommodated in the branch line with a balanced mode of a high level data link control means (HDLC) in using the address part of a frame. CONSTITUTION:An SABM frame from a terminal 2c enters a monitor register 20a via a separation centralized circuit 18f. When the branch circuit is not jammed, a control circuit 26 opens a gate circuit 19e, a part A of the frame represents ''EX direction'' with the operation of a frame insertion circuit 24 and reset to the branch number from ''1''. The SABM frame reaches the EX via a separation centralized circuit 18b and the branch line 1. Further, an UA frame from the EX is stored in a monitor register 20b with a separation and centralized circuit 18a. the part A of the UA frame is compared at a discrimination circuit 21 with the branching number of a branch number register 22, and when the both are equal, a control circuit 26 operates a frame branch circuit 25 and branches the UA frame. |
