The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 27, 1991
Filed:
Jul. 06, 1990
John R Aggers, Apple Valley, MN (US);
Roger R Roth, Minnetonka, MN (US);
Honeywell Inc., Minneapolis, MN (US);
Abstract
A communications system has an active master node which transmits request messages in serial bit fashion on a data bus, and a plurality of responder nodes each of which receives the request messages on the data bus and may respond to a request message with a serial bit answer message. The possiblity exists that a plurality of responder nodes may provide concurrent answer messages forming a composite signal which the active master node may not be able to recognize as containing answer messages. A low pass filter is provided in the active master node which provides as its output only those pulses in the composite signal whose length is within a predetermined interval, typically from approximately a tenth to one half of the interval for each bit in the answer messages. A counter receives the low pass filter output and provides a collision signal to the associated master node if more than a preselected number of pulses within the predetermined interval are present. By providing the collision signal only after detecting a plurality of these pulses in the low pass filter output, it is possible to avoid false detection of concurrent answer messages whose presence is simulated by noise on the line.