GB2210217A

GB2210217A - Computer software controlled power supply switch

Info

Publication number: GB2210217A
Application number: GB8822243A
Authority: GB
Inventors: David Alexander Rippon Wallace
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-09-23
Filing date: 1988-09-22
Publication date: 1989-06-01
Also published as: GB8822243D0; GB8722400D0

Abstract

A computer system 10 is powered from electrical power lines 12 via a switch 16 which is opened on the basis of a data signal derived from the system 10 via line 24. The data signal may be produced in response to completion of a program, and arrangements may be included to ensure an orderly shutdown. <IMAGE>

Description

SOFTWARE CONTROLLED SWITCH AND METHOD This invention relates to a software-controlled switch and to a method of controlling a computer.

With the increasing utilisation of small computers in a modern office, users often find that a long-run program such as report printing, database sorting, wage runs, etc. has to be started at the end of the working day to avoid occupying computer time in normal office hours.

This is also applicable to small process control systems etc. The computer itself does the task, but staff have to stay on, or return late at night, say, to ensure that the equipment is switched off at the end of the program run to fulfil fire precautions, avoid unnecessary use of power etc. This need to attend the computer at the end of a run costs money or at least causes inconvenience.

A simple time switch could be used to cut off the power after a given time but a set task often takes longer than expected and the computer could be turned off before the end of the program necessitating a complete re-run and possibly requiring recovery of corrupted files due to a shut down occurring during the program run. Additionally if the power supply to a computer system fails during a program run and then comes on again, it is possible for not only the program and data files to be corrupted due to such an unsupervised restart but also for hardware to be damaged e.g hard disk systems may have head crashes due to the absence of a properly controlled start up.

The present invention overcomes these inconveniences and disadvantages by controlling the power supply to the computer in such a way that the power is terminated at the end of the program run by an instruction from the computer itself. Alternatively, or in addition, if the power should fail during the time the computer is operational, no power will pass through to the computer system until the controller has been reset even though the main power supply has been restored.

Thus in one aspect the invention comprises an electrical power supply switch for a computer which includes power input means for connection to a power supply, power ou#tput means for connection to a computer system and switch means disposed therebetween, the switch means being adapted to be operated by a signal received from the computer system.

Conveniently the switch means comprises a solenoid coil in circuit with an electrical control unit, the control unit receiving its necessary power supply from a point which is electrically " "downstream" of the switch means.

In its method aspect, the invention involves controlling a computer system from a power supply via a switch means which is itself controlled by the computer system.

The switch means can be a single switch (e.g. relay-controlled) which interrupts the entire power supply to the system in a single unified act or a plurality of switches which act sequentially to deprive separate parts of the system of power in accordance with a pre-arranged sequence.

The invention will now be further described, by way of example, with reference to the accompanying drawing, the sole figure of which is a software controlled switch with no-volt cut out.

Referring to the drawing, electrical power is fed to a computer system 10 from a supply network (not shown) via live (L) and neutral (N) lines 12 and a switch means 14. The switch means 14 includes a contact 16 in the live line L which is controlled by a relay 18 (e.g. having a solenoid coil 20). Energising power for the relay 18 is derived from the lines 12 from a control unit 22 (e.g.

an electronic control unit) which is linked to the computer system 10 via a data line 24 containing a control bypass switch 26. The line 24 can connect to any convenient output port of the computer system (e.g. the transmit connection on an RS232 serial port).

Power to the control unit 22 and relay 18 is taken from the mains supply "downstream" of the switch means 14. There is a start/reset button 28 disposed in parallel with the contact 16.

Initially the computer system 10 and the switch electronics unit 22 are completely isolated from the mains supply by the relay-controlled switch means 14. When the start/reset button 28 is operated, power is supplied to the controlling electronics unit 22 causing the relay 18 to be operated and hold the contact 16 in its closed condition passing power to the connected computer system 10. This then is the normal operating state and the connected equipment can be freely used and operated.

If the mains power should fail, the relay 18 will no longer be able to hold the contact 16 in the ON state and will isolate the whole system from power even when the mains supply returns until such time as the start/reset button 28 is pressed.

If, while the software switch 26 is in its closed state (i.e. passing signals) a suitable signal is received from the computer system 10, this is used to turn the relay 18 off, isolating the system 10 and unit 22 from the mains supply until the start/reset button 28 is again pressed. The control bypass switch 26 is used to turn off the input from the computer system 10 in circumstances where it is desired to ensure the power remains on despite signals from the computer system. Suitable "Power Down" control signals could be derived from a small program sitting in the memory of the connected computer monitoring the Central Processing Unit activity so that when all data processing activity has ceased the program causes a signal (e.g. a 'high' level) to be sent on the line 24.

The line 24 could be an electrically conducting cable as shown but it could also be an optical fibre, a radio link or a suitable pulse transmitted through the air, since all that it required is the transmission of a data signal to energise the relay 18 via the control unit 22.

The software of the computer system 10 desirably includes instructions for an orderly closing down of the main program being operated. Thus, for example, all open files would be closed off and saved and instructions produced to return the computer to the BIOS/DOS prompt. These or other actions ensure an orderly exit to a condition where it is possible to close down the system without data loss. The software may also be arranged to create a file of the entire contents of the memory and/or just the data displayed on the screen just prior to close down to enable recovery to the exact situation existing prior to close down should such be required.

Although control of a computer system is likely to be the main application of the invention it is not ruled out that other forms of equipment capable of generating an "end power supply" signal could also be used for the unit 10.

Double pole switches (in lines L and N) can clearly be used as could a three-phase arrangement.

Claims

1. An electrical power supply switch for a computer which includes power input means for connection to a power supply, power output means for connection to a computer system and switch means disposed therebetween, the switch means being adapted to be operated by a signal received from the computer system.

2. A switch as claimed in claim 1, in which the switch means comprises a solenoid coil in circuit with an electrical control unit, the control unit receiving its necessary power supply from a point which is electrically "downstream" of the switch means.

3. A switch as claimed in claim 1 or claim 2, in which the switch means is a single switch which interrupts the entire power supply to the system in a single unified act.

4. An electrical power switch for a computer substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawing.

5. A method of controlling a computer system from a power supply via a switch means, characterised in that the switch means is itself controlled by the computer system.

6. A method as claimed in claim 5,in which the switch means comprises a solenoid coil in circuit with an electrical control unit, the control unit receiving its necessary power supply from a point which is electrically "downstream" of the switch means.

7. A method as claimed in claim 5 or claim 6, in which the switch means is a single switch which interrupts the entire power supply to the system in a single unified act.

8. A method as claimed in claim 5 or claim 6, in which the switch means is a plurality of switches which act sequentially to deprive separate parts of the system of power in accordance with a pre-arranged sequence.

9. A method of controlling a computer system from a power supply substantially as herein described with reference to the accompanying drawing.