公开(公告)号：US3435142A

公开(公告)日：1969-03-25

申请号：US3435142D

申请日：1965-08-16

Applicant: BELL TELEPHONE LABOR INC

Inventor： CROWSON FRED B ,  GROTH GEORGE S

IPC: H04L5/00 ,  H04L25/20 ,  H04L15/00 ,  H04L25/52

CPC classification number: H04L5/00

公开(公告)号：US3623019A

公开(公告)日：1971-11-23

申请号：US3623019D

申请日：1969-11-26

Applicant: BELL TELEPHONE LABOR INC

Inventor： GROTH GEORGE S

IPC: G06F13/22 ,  H04L12/50 ,  H04Q3/545 ,  G06F9/18

CPC classification number: H04Q3/54591 ,  G06F13/22 ,  H04L12/50

Abstract: Multiple, multistation, data lines are independently operable when polling the stations on each line to determine their readiness for communication. Each polling interrogation signal applied to a line causes the storage of a line-timing status bit in one of two duplicate memories in a supervising office. Each such memory contains one bit location per data communication line. Upon the occurrence of a station response to the interrogation, the timing status bit for the corresponding line is erased from memory. The two memories are alternately utilized for receiving timing bits during recurrent periods which are equal to a minimum allowable timeout interval for a station. Prior to each such use, a memory is scanned to detect any timing bits persisting therein and thereby indicating a timeout condition on the corresponding line. Such a condition further indicates a need for a special control routine for the timed out station. Both apparatus and program embodiments of the invention are disclosed.