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Browse Prior Art Database

Synchronous Coupling of Asynchronous Devices in the Presence of Noise

IP.com Disclosure Number: IPCOM000104500D
Original Publication Date: 1993-Apr-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 1 page(s) / 64K

Publishing Venue

IBM

Related People

Colson, JC: AUTHOR [+5]

Abstract

Disclosed is a method for synchronizing devices that communicate asynchronously in a noisy environment, making extra or missing messages commonplace. In real time control environments, control of asynchronous processes is managed explicitly. In noisy environments, different devices may have different signal thresholds than the control system. Unsolicited responses from either device may corrupt the unsuspecting system.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Synchronous Coupling of Asynchronous Devices in the Presence of Noise

      Disclosed is a method for synchronizing devices that
communicate asynchronously in a noisy environment, making extra or
missing messages commonplace.  In real time control environments,
control of asynchronous processes is managed explicitly.  In noisy
environments, different devices may have different signal thresholds
than the control system.  Unsolicited responses from either device
may corrupt the unsuspecting system.

      In the current embodiment, the method is used for synchronizing
a bar code printer and a bar code scanner to a control system that
monitors a demographic bindery line.

      The process of controlling a barcode printer is implemented by
synchronizing the events of three asynchronous processes.  Initially,
the barcode is preassigned to the barcode printer.  When this
assignment is made, no assumption about the validity of the product
is made, either location or existence.  The first process also writes
the current location into a mailbox, to be read by the synchronizing
process.  Upon receipt of the response from the barcode printer
acknowledging completion of the barcode print, the current position
is read and the difference between that value and the previous value
verifies whether the slot is the same or has been increased.  Only
after the product has been verified as good does the assignment of
the barcode to that products' information take place.  If the
response was unsolicited, where th...