Browse Prior Art Database

Automatic Speed Changing System Based Upon Timeouts

IP.com Disclosure Number: IPCOM000086043D
Original Publication Date: 1976-Jul-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Bederman, S: AUTHOR [+2]

Abstract

This speed changing system allows a downstream terminal in a data communications loop to automatically adjust its data rate to conform with the data rate of an upstream station or the primary station. The terminal, when inserted into the loop, can be set up to receive and transmit data at one of multiple data rates. The data rate selection is controlled by one of several speed latches which correspond to the available speed settings.

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Automatic Speed Changing System Based Upon Timeouts

This speed changing system allows a downstream terminal in a data communications loop to automatically adjust its data rate to conform with the data rate of an upstream station or the primary station. The terminal, when inserted into the loop, can be set up to receive and transmit data at one of multiple data rates. The data rate selection is controlled by one of several speed latches which correspond to the available speed settings.

The present system causes the terminal to run through a series of microcode subroutines when first inserted into the loop. During the first subroutine the terminal speed is set at the highest available speed, and the subroutine determines whether the incoming data is in synchronization at the highest speed. If the terminal is in sync, a message detect time out is initiated and if a message is received within the time out interval the terminal remains at the current data speed.

If a message is not received within the time out interval, the terminal is reset to the next lower speed and a subroutine corresponding to that speed is initiated. The process is repeated so long as the incoming data is in synchronization until the terminal has been set at all possible speeds. If a message is not detected at any of the speeds an alarm subroutine is initiated.

If the incoming data is out of synchronization at the start of any of the subroutines an out-of-sync time out is initiated, whereby sync...