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公开(公告)号：JPS62169537A
公开(公告)日：1987-07-25
申请号：JP27551986
申请日：1986-11-20
Applicant: IBM
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公开(公告)号：DE3687792D1
公开(公告)日：1993-03-25
申请号：DE3687792
申请日：1986-12-18
Applicant: IBM
Inventor： MELTZER CLIFFORD BENNETT , KANNAN KRISHNAMURTHI , BURKET THOMAS GERARD , KRUESI DEBORAH JEAN , BRAUDAWAY GORDON WESLEY
Abstract: Automatic detection of and recovery from errors of transmissions in the form of a sequence of data packets is described as well as an improved combination of end-of-text (ETX) bytes along with checksums in each data packet to detect errors. The ETX character (12) is dynamically selected for each packet after the data comprising the packet has been assembled. This character is coded differently from the remaining character codes in its respective packet and is made the second byte thereof following the start-of-text byte (STX). The third byte (3) in each packet is made the complement of the preceding ETX byte, the latter of which is also made the last byte in the packet. Other bytes in each packet include: one byte (4) indicating the location of the packet in a set in a given transmission sequence; a byte (7) distinguishing the packet's set from other transmission sequences; two bytes (5,6) indicative of the number of data bytes in the packet; one byte (8) operating as a control character indicating the functional nature of the packet; data bytes; and two checksum bytes (9,10+m) which precede the last ETX byte. Upon detection of an error in a packet, the transmitter is immediately notified and retransmission is carried out only from the erroneous packet rather than from the beginning of the entire sequence as in the prior art.
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公开(公告)号：DE3687792T2
公开(公告)日：1993-08-19
申请号：DE3687792
申请日：1986-12-18
Applicant: IBM
Inventor： MELTZER CLIFFORD BENNETT , KANNAN KRISHNAMURTHI , BURKET THOMAS GERARD , KRUESI DEBORAH JEAN , BRAUDAWAY GORDON WESLEY
Abstract: Automatic detection of and recovery from errors of transmissions in the form of a sequence of data packets is described as well as an improved combination of end-of-text (ETX) bytes along with checksums in each data packet to detect errors. The ETX character (12) is dynamically selected for each packet after the data comprising the packet has been assembled. This character is coded differently from the remaining character codes in its respective packet and is made the second byte thereof following the start-of-text byte (STX). The third byte (3) in each packet is made the complement of the preceding ETX byte, the latter of which is also made the last byte in the packet. Other bytes in each packet include: one byte (4) indicating the location of the packet in a set in a given transmission sequence; a byte (7) distinguishing the packet's set from other transmission sequences; two bytes (5,6) indicative of the number of data bytes in the packet; one byte (8) operating as a control character indicating the functional nature of the packet; data bytes; and two checksum bytes (9,10+m) which precede the last ETX byte. Upon detection of an error in a packet, the transmitter is immediately notified and retransmission is carried out only from the erroneous packet rather than from the beginning of the entire sequence as in the prior art.
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