GB2271897A

GB2271897A - Bistable relay circuit

Info

Publication number: GB2271897A
Application number: GB9221449A
Authority: GB
Inventors: Joe Mcardle; Simon Cheung
Original assignee: Honeywell Control Systems Ltd
Current assignee: Honeywell Control Systems Ltd
Priority date: 1992-10-13
Filing date: 1992-10-13
Publication date: 1994-04-27
Anticipated expiration: 2012-10-13
Also published as: GB2271897B; GB9221449D0

Abstract

In a heating controller, each of ports 1 and 5 of microprocessor 7 is able to operate two functions, namely the temperature sensing of one location and also the switching on and off of e.g. the boiler or the pump. This is achieved by bi-stable relays 8 and 9 arranged so that the other ports can effect reverse polarity of the relays. In this way, six ports can achieve the operation of two appliances and the temperature sensing of two locations, this conventionally requiring ten ports. <IMAGE>

Description

80LID-STATE DEVICE The present invention relates to a solid-state device, and to a method of operating such a device.

Typically, electrical products use general-purpose mass-produced microprocessors which have a fixed number of input/output ports to interface with other circuit components and devices.

Particularly in products or systems involving multiple functions, interfacing or sensing, there may be an insufficient number of input/output ports, even though the processing capacity of the microprocessor is more than adequate. Thus, it is necessary to consider whether to use a special-application/customised microprocessor with a greater number of ports, or to use a bigger general-purpose microprocessor with more processing power and more ports.

Either solution involves significant additional cost.

The present invention provides an electronic solidstate data processing device having at least one input or output port connected to a plurality of lines for linkage to separate devices and for carrying functionally-different signals.

In one form, an electronic solid-state data processing device comprises a plurality of input and output ports to interface between circuitry internal to the device and other devices, and means to allow at least one of said ports to connect with a plurality of lines for linkage to separate devices and for carrying functionally-different signals.

In this way, a port can be used for more than one line so that more functions can be incorporated into a device without having to uprate the microprocessor or resort to customised microprocessors.

Preferably, the invention utilises means to latch the common port selectively to any one of the shared lines; advantageously there is provided means to switch the latch means to another of the shared lines, such switch means may comprise circuitry and/or electrical components connecting one or more ports to the latch means. In preferred embodiments, the device utilizes bi-stable relay means located in a line sharing a common port.

The device may comprise means to effect sensing of a parameter on a line connected to a shared port and/or means to effect sending of an instruction on a line connected to a shared port.

The present invention also provides a method of operating an electronic solid-state data processing device with a plurality of input and output ports to interface between circuitry internal to the device and other devices, the method comprising using at least one input or output port selectively for a plurality of lines for linkage to separate devices and for carrying functionally different signals.

Preferably the method comprises latching a common port selectively to any one of the shared lines; it may further comprise switching a common port to any one of shared lines.

Preferably the method comprises using bi-stable relay means located in a line sharing a common port.

Advantageously the method comprises effecting sensing of a parameter using a line connected to a shared port, and/or effecting sending of an instruction using a line connected to a shared port.

The present invention is applicable to any suitable electronic solid-state data processing device, including microprocessors, data stores and data input/output interfaces, and is suited to a wide variety of situations and applications, including: controllers of systems and networks or telecommunications equipment and systems.

The invention is suited to achieving multiple use of a port as an input port or multiple use of a port as an output port, as well as enabling a given port to be used both as an input and as an output port.

Forms of relay means other than bi-stable relays may be utilized; for example a switching component requiring two or more connections to completely determine its operating state may be used. In an alternative form, there may be used mono-stable relays with appropriate additional circuitry and with switching signals durations substantially less than the relay "pull-in" time.

In order that the invention may more readily be understood, a description is now given, by way of example only, reference being made to the sole accompanying Figure being a block circuit diagram of apparatus embodying the present invention.

Conventionally, four ports of the microprocessor in a domestic heating system controller are required to operate a bi-stable relay used for remote appliances, and two additional ports are required to operate sensing of one remote location. The sole Figure shows circuitry of part of a domestic heating system controller embodying the invention and having an arrangement of six ports 1 to 6 of a microprocessor 7 such that port 1 is able to operate two functions, namely the temperature sensing of one location and the switching on and off of the boiler. Likewise, port 5 is able to operate two functions, namely the temperature sensing of another location and the switching on and off of the pump. Thus a total of six ports achieve the operation of two appliances and the temperature sensing of two locations, this conventionally requiring ten ports.

In this embodiment, this multiple functioning of lines 1 and 5 is achieved by having bi-stable relays 8 and 9 respectively arranged so that the other ports can effect reverse polarity of the relays. Thus each bi-stable relay 8 and 9 latches into position and stays there after the exitation voltage has been removed it can only be switched back by applying a voltage of the opposite polarity. As long as the relay can be isolated at either its positive or negative terminal it cannot switch. For example it does not matter if port 1 is used to control the thermistor channel select and thus causes relay 8 "-" terminal 23 to go THIGH, relay 8 will be isolated anyway at its "+" terminal 22 since port 3 is held LOW.

Relay 8 is operated by the circuit formed by pull-up resistors 10 to 13, base resistors 14 to 17, transistors 18 to 21 and terminals 22, 23 ("+" and "-" respectively as shown), having the valid states for switching relay 8 as in the following truth table referenced TABLE 1.

Relay 9 shares the same "+" relay connection (i.e.

terminal 22), the extra circuitry to provide the '-" relay drive being pull-up resistors 24, 25, base resistors 26, 27, transistors 28, 29 and terminal 30 (relay 9 "-" connection); the valid states for switching relay 9 are in TABLE 1.

Thus, transistors 19, 20 and associated components are utilised in the circuits of both relays 8 and 9, and contribute to the reduction in the number of ports required.

The dual functions of ports 1 and 5, which involve controlling the relay drive transistors 18 and 28 and also controlling the A/D converter, is possible because each bi stable relay only needs to be isolated at either its "+" or | terminals, the software within microprocessor 7 ensuring that a A/D conversion never takes place when a relay is switching, and vice versa.

Base resistor 32, transistor 33 and port 31 are additional switch components that stop current drain through pull-up resistors 11, 12 and 25 during the "No Operation state in TABLE 1. Buffers 34 and 35 control an astable multi-vibrator circuit used in temperature measurement.

TABLE1 Terminals STATE PORT 31 PORT 1 2 3 4 PORT 5 6 22 23 30 No Operation H H H L L H L Z Z Z Relay 8 Close L H L L H H L H L Z Relay 8 Open L L H H L H L L H Z Relay 9 Close L H L L L H H H Z L Relay 9 Open L H H H L L L L Z H A/D Control: Termistor Sel. H L H L L H L Z H Z ReE Channel Sel. H H H L L L L Z Z H (H = High voltage lcvel,L = Low voltage Icvel, Z = High impedance, * = Dual function port

Claims

CLAINS

1. An electronic solid-state data processing device having at least one input or output port connected to a plurality of lines for linkage to separate devices and for carrying functionally-different signals.

2. An electronic solid-state data processing device comprising a plurality of input and output ports to interface between circuitry internal to the device and other devices, and means to allow at least one of said ports to connect with a plurality of lines for linkage to separate devices and for carrying functionally-different signals.

3. A device according to Claim 1 or 2, comprising means to latch the common port selectively to any one of the shared lines.

4. A device according to Claim 3, comprising means to switch the latch means to another of the shared lines.

5. A device according to Claim 4, wherein the switch means comprises circuitry and/or electrical components connecting one or more ports to the latch means.

6. A device according to any preceding Claim, comprising bi-stable relay means located in a line sharing a common port.

7. A device according to any preceding Claim, comprising means to effect sensing of a parameter using a line connected to a shared port.

8. A device according to any preceding Claim, comprising means to effect sending of an instruction using a line connected to a shared port.

9. A method of operating an electronic solid-state data processing device with a plurality of input and output ports to interface between circuitry internal to the device and other devices, the method comprising using at least one input or output port selectively for a plurality of lines for linkage to separate devices and for carrying functionally-different signals.

10. A method according to Claim 9, comprising latching a common port selectively to any one of the shared lines.

11. A method according to Claim 9 or 10 comprising switching a common port to any one of the shared lines.

12. A method according to any of Claims 9 to 11 comprising using bi-stable relay means located in a line sharing a common port.

13. A method of operating an electronic solid-state data processing device substantially as hereinbefore described with reference to and/or as illustrated in the sole accompanying Figure.

13. A method according to any of Claims 9 to 12, comprising effecting sensing of a parameter using a line connected to a shared port.

14. A method according to any of Claims 9 to 13, comprising effecting sending of an instruction using a line connected to a shared port.

15. An electronic solid-state data processing device substantially as hereinbefore described with reference to and/or as illustrated in the accompanying drawing.

16. A method of operating an electronic solid-state data processing device substantially as hereinbefore described with reference to and/or as illustrated in the accompanying drawing.

Amendments to the claims have been filed as follows

1. An electronic solid-state data processing device having at least one input or output port and bi-stable relay means to effect selective connection between said port and a plurality of lines for linkage to separate devices and for carrying functionally-different signals.

2. An electronic solid-state data processing device comprising a plurality of input and output ports to interface between circuitry internal to the device and other devices, and bi-stable relay means to allow at least one of said ports to connect with a plurality of lines for linkage to separate devices and for carrying functionally-different signals.

3. A device according to Claim 1 or 2 wherein the bistable relay means is effective to latch the common port selectively to any one of the shared lines.

4. A device according to Claim 3, wherein the bistable relay means is effective to switch to another of the shared lines.

5. A device according to any preceding Claim, comprising means to effect sensing of a parameter using a line connected to a shared port.

6. A device according to any preceding Claim, comprising means to effect sending of an instruction using a line connected to a shared port.

7. An electronic solid-state data processing device substantially as hereinbefore described with reference to and/or as illustrated in the sole accompanying Figure.

8. A heating system controller comprising an electronic solid state data processing device according to any preceding Claim.

9. A method of operating an electronic solid-state data processing device with a plurality of input and output ports to interface between circuitry internal to the device and other devices, the method comprising operating a bistable relay means to selectively use at least one input or output port for a plurality of lines for linkage to separate devices and for carrying functionally-different signals.

10 . A method according to Claim 9, comprising operating the bi-stable relay means to latch a common port selectively to any one of the shared lines.

11. A method according to Claims 9 or 10, comprising effecting sensing of a parameter using a line connected to a shared port.

12. A method according to any of Claims 9 to 11, comprising effecting sending of an instruction using a line connected to a shared port.