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Browse Prior Art Database

On/Off Line Relay Control Logic

IP.com Disclosure Number: IPCOM000079340D
Original Publication Date: 1973-Jun-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Ballou, DC: AUTHOR

Abstract

All devices that attach to IBM System/360 or IBM System/370 computers are required to have select-out bypass relays, which are used when the device powers up or down or goes on or off-line. The on/off-line relay control logic operates the select-out bypass relays. This logic meets the minimum requirements of the system architecture, power systems, and in addition, offers the important advantage of not disrupting system communication on fault power-off conditions such as: circuit breaker overload, thermal sensor power off, or an improper operator power-down sequence.

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On/Off Line Relay Control Logic

All devices that attach to IBM System/360 or IBM System/370 computers are required to have select-out bypass relays, which are used when the device powers up or down or goes on or off-line. The on/off-line relay control logic operates the select-out bypass relays. This logic meets the minimum requirements of the system architecture, power systems, and in addition, offers the important advantage of not disrupting system communication on fault power- off conditions such as: circuit breaker overload, thermal sensor power off, or an improper operator power-down sequence.

The flow chart (Figs. 1a and 1b) shows the sequence of events to control the select-out bypass relays. On a normal power off when on-line, the logic waits until the off-line conditions are met, then properly sequences the relays to their off-line position. If the off-line conditions are not met, the device remains on-line and powered up. On a fault power off, the control logic goes through a delay loop (States 6 through 10). This loop allows time for the off-line conditions to be met; then at the end of the loop, the relays are sequenced to off-line even though the off-line conditions are not met. This insures that the device will always be off- line when power drops, which is necessary to prevent disrupting the system.

The one/off-line control logic hardware requires no single-shots, delays or adjustments. Each circled number on the flow chart is a state decoded from...