GB2357380A - Power distribution system - Google Patents

Abstract

Power is supplied to a number of modules 40, 68, 102 at a plurality of voltages from a base power supply module 20. The modules consist of a mains control module 40 (see figure 5) which outputs mains power to a device (pump 188, figure 15) based on a control input from a timer module 102 (see figures 9 and 10) generates the timer module control input for the mains power module for a user set duration based on a trigger signal. The trigger signal is provided to the timer module by a switch module 68 (see figure 8) which is connected to a switch (184, figure 15) which relates to a requirement for the device to be powered. The system is used to power laboratory equipment (figure 15) based on an input to the switch to control a long running experiment which would otherwise require intervention by a technician.

Description

257380 CONTROL SYSTEM The present invention is concerned with a control

system and has particular, but not exclusive, application to the control of laboratory equipment.

The use of electrical and electronic equipment has become increasingly widespread in the last few years.

Many processes, which would have previously been carried out by hand, can now be conducted using autonomous or automatic equipment.

For example, in a chemical or biological procedure, it is common for a substance to require delivery to equipment over a considerable period of time. Delivery might need to be at a substantially constant rate, or it might need to be maintained such that the amount of that substance within the equipment does not fall below a certain level. Delivery might originally have been conducted by pouring the substance into the equipment manually, but a present day implementation might include a provision of an electric pump to assist the technician conducting the procedure.

Moreover, other functions, such as stirring, which might have been conducted by hand, can now be conducted by use of electric equipment. An electric stirrer might include means for vibrating a vessel containing a liquid, and/or means for generating a rotating magnetic field

2 within the vessel and placing steel objects within the vessel which will be agitated by the rotated magnetic field.

Other electric or electronic equipment encountered in a laboratory might include PUMPS, heaters, refrigerators, cooling baths and fans.

Since the above equipment can be run substantially continuously, it is possible to conduct relatively time consuming laboratory procedures with comparative ease.

However, the laboratory technician needs to be present at all times, in order to monitor the equipment and to ensure, for instance if a heater is being used, that the substance being heated remains within a desired temperature range. This can place onerous responsibilities on the laboratory technician. If,the laboratory technician needs to perform other tasks, which means that he must withdraw his attention from the equipment in question, the problem arises in that the equipment must either be switched off or must be monitored by an assisting technician. It may not always be practical to switch the equipment off, since the procedure may not necessarily be interruptible.

Moreover, an assisting technician may not always 'be available.

3 Therefore, it has become necessary to provide automated laboratory equipment so that technicians can be relieved to perform other tasks. However, since laboratory equipment tends to be manufactured in relatively small quantities, automated laboratory equipment tends to be very expensive. This is particularly a problem in that a laboratory technician working in a chemistry or bio-technology laboratory might not have the requisite training in order to operate complicated electronic equipment. Therefore, there is a need to provide automated laboratory equipment in a form which is relatively straightforward to operate. This requirement can lead to quite complicated electronic solutions.

The design and implementation of control circuitry to be placed within automated laboratory equipment can contribute to very high product costs. This is particularly a problem in the field of laboratory equipment, where manufacturing volumes may be quite small and so the electronics design costs can only be spread over a small number of items.

Accordingly, the automation of laboratory equipment leads to a conflict between providing a piece of equipment which is relatively easy to use and providing equipment at relatively low costs.

4 The present invention aims to address the problems set out above.

According to a first aspect of the present invention, there is provided a modular control system comprising a base module and a plurality of depending modules wherein:

the base module comprises power supply means having an input to receive power at a predetermined first voltage and a plurality of outputs to provide output power signals at a plurality of predetermined output voltage levels; and each depending module comprises power input means for receiving each of said plurality of output power signals; control signal input means for receiving an input control signal; main signal output means for outputting one or more main signals; switch means for selectively connecting the power input means to the main signal output means whereby the main signal output means may selectively output one or more of said output power signals as one or more output main signals; and control means; wherein the control means is operable to alter the configuration of the switch means to change at least one of said output main signals.

Note, that the control means may control the switch means to change at least one of said output main signals from one of the output power signals to another or it may disconnect or connect one of the output power signals to or from a floating state.

Preferably, at least one of the depending modules is a sensor module wherein said control signal input means comprises a sensor input means for receiving a sensor input signal from a sensing device and wherein the switch means is adapted to selectively connect either a control voltage output power signal or a ground voltage output power signal to the main signal output means.

Preferably, at least one of the depending modules is a control module wherein the switch means is adapted either to connect a driving output power signal for driving an external device from the power input means to the main signal output means or to disconnect the driving output power signal from the main signal output means whereby the external device may be selectively driven or not in dependence on the configuration of the switch means. Preferably, the switch means of the control module comprises a relay.

Preferably, each depending module further includes power output means connected to said power input means for outputting each of said output power signals. In 6 this way, a number of depending modules may be linked together with appropriate linking cables between the power output means of one module and the power input means of another (depending) module.

Preferably, there are at least three different output power signals such as, for example, 230V AC at a maximum amperage of say 6 Amps, +5V DC (to provide a high TTL control voltage) and OV DC (to provide a low TTL control voltage).

By providing for the automatic control of laboratory equipment by means of modular control equipment, it is possible to present a technician with suitably designed modules such that the solution to the technician's problem can be constructed by the technician without expert assistance. Moreover, modules can be provided in such a manner that they can be used in a number of different applications, and so application-specific electronics and software is not required. It is the fact that prior automated equipment requires application specific control hardware and software that increases the cost of automated equipment.

Preferably, the sensor module is adapted to receive the sensor input signal from a sensing device associated with a piece of external equipment and the control module is adapted to generate the control output signal for 7 controlling a piece of external equipment. The sensor and control modules may be connected directly, in which case, the control module may be configured to switch the power output means in direct dependence on an input signal received at the sensor module. Alternatively, an intermediate module may be provided, so as to process the signal received at the input of the sensor module and to control the control module to generate its output main signal on the basis of the processed input signal. The intermediate module may consist of logic means, whereby a plurality of sensor modules are connectable therewith, such that the control module is configured to generate its output main signal on the basis of a logical operation of the input signals received by the sensor module or modules, in use. Furthermore, the intermediate module may include timing means, the timing means being operative to present a signal to the control module such that the main signal generated in use by the control module is time dependent. The timing means may be configured such that the main signal generated in use by the control module comprises a pulse of predetermined duration. The timing means may include timing adjustment means such that the duration of a pulse can be adjusted by a user.

8 The timing adjustment means may, in addition or alternatively, include delay means, to inhibit the production by the control module of its main signal for a predetermined period of time. The delay means may include delay adjustment means to allow a user to adjust the predetermined time delay.

Further aspects and advantages of the invention will be appreciated from the following description of preferred embodiments of the invention by way of example only, and with reference to the accompanying drawings, in which:

Figure I is a perspective view of a base module and rack in accordance with a first specific embodiment of the invention; Figure 2 is a front view of a portion of the base module and rack as illustrated in Figure 1; Figure 3 is a circuit diagram of the base module and rack illustrated in Figure 1; Figure 4 is a perspective view of a supplementary rack in accordance with the first specific embodiment of the invention; Figure 5 is a front view of a mains control module in accordance with the first specific embodiment of the invention; 9 Figure 6 is a perspective view of the mains control module illustrated in Figure 5; Figure 7 is a front view of a low voltage control module in accordance with the first specific embodiment of the invention; Figure 8 is a front view of a switch module in accordance with the first specific embodiment of the invention; Figure 9 is a front view of a time delay module in accordance with the first specific embodiment of the invention; Figure 10 is a f ront view of a time duration module in accordance with the first specific embodiment of the invention; Figure 11 is a front view of a sensor trigger module in accordance with the first specific embodiment of the invention; Figure 12 is a front view of a multifunction timer module of the first specific embodiment of the invention; Figure 13 is a front view of a logic module of the first specific embodiment of the invention; Figure 14 is a f ront view of an example of the implementation of the first specific embodiment of the invention; Figure 15 is a circuit diagram of the implementation illustrated in Figure 14; Figure 16 is a schematic f ront view of an example of an implementation of a second specific embodiment of the invention; Figure 17 is a schematic rear view of the implementation of the second specific embodiment of the invention shown in Figure 16; Figure 18 is a circuit diagram of a base module according to the second specific embodiment of the invention; Figure 19 is a wiring diagram illustrating the wiring between a power input means and a power output means of a depending module according to the second specific embodiment of the invention; Figure 20 is a circuit diagram of a 6 Amp AC mains output control module of the second specific embodiment of the invention; and Figure 21 is a circuit diagram of a switch innut sensor module according to the second specific embodiment of the invention.

Turning f irstly to Figure 1, a base module and rack comprises a generally cuboidal metal box, with one open side 12. An inwardly directed f lange 14 extends around the edge defining the open side 12. As 11 illustrated in Figure 1, the height of the rack 10 can be considered to be divided into five equal sections 16.

Located in the f ace of the rack opposite the open f ace 12 is a series of five D-type connectors 18. These are best illustrated in Figure 2.

The lower-most of the five sections 16 is occupied by a power supply 20. The power supply 20 has a connector (not shown) to connect with the D-type connector 18 in the back wall of the rack and corresponding with the lower section 16 of the rack. The power supply 20 receives mains power through a cable 22. The power supply includes a transformer and rectifier so as to provide vol.:p,,,.12 volts and 24 volts DC power rails, and also includes residual current detection through which the main-.-power supply is passed and onto the other four d-type.connectors 18. As shown in Figure 2, a group of three,larger pins 22 is provided in each of the D-type connectors 18. These pins are used to present live, neutral and earth supply at AC mains directing to any unit installed in each of those sections 16 of the rack corresponding to those D-type connectors 18. The volts, 12 volts and 24 volts DC rails are supplied to the other six pins, taking account of the fact that the DC rails will require zero volt lines as well.

12 The front face of the power supply 20 includes three neons 24, which light when the 5 volt, 12 volt and 24 volt power supply rails respectively are switched on.

Furthermore, a reset button 26 is located on the front face of the power supply 20, which reset button 26 can be pressed if the residual current detection unit trips the power supply 20.

An illuminated on/off switch 28 is also provided.

This switches in the live voltage received along the main supply 22 to the power supply of the unit 20.

Figure 3 illustrates in more detail the wiring arrangement of the rack 10. An earth line extends from the main supply lead 22 throughout the rack and is connected to each of the D-type connectors 18. A residual is current protection unit 30 receives the live and neutral line, and is itself connected to the other two of the larger pins 23 of the D-type connectors 18. It will be understood that the DC power supply rails will be wired in the rack in much the same way.

The rack further comprises along the inwardly extending flange 14 a series of holes 32. The holes 32 are located so that a module can be inserted into one of the sections 16 of the rack 10, and can be fixed in place by means of screws at each of the four corners of the front face of the module, and through the hole steady to.

13 For ease of fixing the holes include tapped portions so that nuts need not also be provided.

The upper side of the power supply unit 20 includes a series of dove tail shape ribs 34 which extend longitudinally and in parallel the full length of the power supply unit 20. The dove tail shape ribs operate to define dove tail shaped grooves 36. The ribs 34 and grooves 36 are to operate with corresponding grooves and ribs on the underside of a module to be placed above the power supply unit 20, to aid location.

A supplementary rack 100 is illustrated in Figure 4.

This rack does not possess a power supply, and relies upon a cross connection from the base module and rack 10 and is illustrated in Figure 1. However, the wiring and is D-type connects are supplied in the back wall of the supplementary rack 100 and as described earlier.

The supplementary rack 100 is capable of receiving up to four modules of single height in this sub-section 16 as described earlier. other features of the supplementary rack 100 which are also provided in the base module and rack 10 are assigned the same reference numerals. Power is supplied to the supplementary rack from the power supply 20 by means of a cross-connection (not shown).

14 The base module and rack 10 and the supplementary rack 100 provide a base for stable bench mounting of control instruments.

With reference to Figure 5, the mains control module 40 will now be described. Furthermore, in Figure 6 the outline of a mains control module is illustrated, to fully demonstrate the longitudinal ribs associated with each of the modules to be described therein. It will be understood that the other modules to be described herein with reference to the first specific embodiment have much the same outline as the main control module 40. The front face 42 of the mains control module 40 has an input socket 44 through which a control signal can be received.

An IEC.type power socket 46 is also provided in the front is face 42. A mode switch 48, capable of being switched into one of three positions, is also provided in the front face 42 of the mains control module.

An output indicator lamp 48, an overload-lamp 50 and a reset- button 52 are further more provided in the front face 42. It is preferred that labels be provided on the front - face to aid the technician who is to use the equipment. Therefore, the labels indicated in the illustration of Figure 5 are suggested. Screws 54 are provided at each of the corners of the f ront f ace 42, for location in the holes 32 of the racks.

The switch 47, as noted previously, is capable of being placed in one of three positions. In a normal-on position, the mains control module is adapted to present 230 volt mains output to the IEC connector 46 when the voltage at the input 44 is being logic low. That is, if TTL logic is used, mains will be supplied when the control input 44 receives substantially 0 volts.

In the normal of f position, the mains control module supplies the mains signal to the IEC connector 46 only when the control input 44 receives a logic high signal that is, in TTL logic, a signal of approximately 5 volts.

The output indicator 48 illuminates when the mains is supplied to the IEC connector 46. The overload lamp 56 illuminates when excessive current is sought from the mains control module 40. In the first specific embodiment described herein, the mains control module has a maximum rating of 4 amps.

In the manual position, the switch 47 configures the mains control module 40 such that mains is supplied at the IEC connector 46 regardless of the signal received at the control input 44. This is useful when manual operation of a device which is controlled from the switched power supply at the connector 46 is desired, for 16 example, if the controlled device is a pump, to allow the pump to primed.

The mains control module 40 will control any mains operated device having rating below the 4 amp level. This covers devices such as motors, pumps, stirrers, fans and heaters. It is useful in that it provides a direct switchable AC power source, when combined with the base module.

With reference to Figure 7, a low voltage control module 56 has a front face 58 as illustrated. In the example illustrated, two alternative low voltage power supplies are provided in the same unit. Features controlled from a control input 60 adapted to the logic signals according to the TTL regime.

Each of the power supplies includes a three position switch 62 as described previously, a pair of connectors 64 for placement of a DC power supply thereon, and an output indicator lamp 66 to indicate when the power supply is supplied to a pair of connectors 64.

In use, each of the switches can be placed in one of a normal-on mode, a manual mode and a normal-off mode.

These three modes switch the DC power supply as the AC power supply is switched in the mains control module 40 described previously. Although in the illustrated example, the left hand power supply supplies a switch to 17 power supply of 0 to 5 volts at 1.5 amps rating and the right hand power supply supplies a switch to the DC power supply of 0 to 12 volts at a rating of 1 amp, alternative and/or additional power supplies can also be provided, such as the 0 to 24 volt power supply provided on the rails on the rack 10, at a rating of 0.5 amps.

The low voltage control module 56 is of use in providing a sel ection of switchable outputs, controllable from the control input 60, to power low voltage DC devices, such as solenoid valves, actuators and small DC motors. All outputs 64 have short circuit protectors against overloading.

With reference to Figure 8 of the drawings, a switch module 68 has a front face 70. A control input 72, a normally on output port 74 and a normally off output port 76 are located in the front face 70. An indicator lamp 78 is provided adjacent output ports 74,76.

A pair of switch input connectors 80 are provided in the front face. A simple switch can be connected across the switch input connectors 80, and circuitry is provided within the switch module 68 to detect open or closed circuit therebetween. A mode switch 82 is provided, the mode switch being positionable in one of two positions, a normally open position and a normally closed position.

In use, the switch module 68 will accept a signal 18 from any simple switch, for example, a positional micro switch, a float switch, a pressure switch or a temperature switch, and converts that signal into a control signal output on one of the output ports 74,76.

In that way, the switch module can be used in conjunction with other modules to control a power supply to another piece of equipment. The mode switch 82 switches between a normally open mode and a normally closed mode. The selection of the appropriate mode is made when considering the type of switch connected across the switch input connectors 80. The control signal previously described will be delivered to one of the normally on output ports 74 and the normally off output ports 76, depending on the state of the switch connected to the switch input connector 80 and the mode in which the switch module 58 is placed. The output indicator lamp 78 is illuminated when the switch connected across the switch input 80 moves out of its normal state whether that be normally open or normally closed.

The control input 72 provides external control, such that a suitable signal can be applied to the switch module 68 to exert a higher level of control over the switch module 68, thus enabling a form of logical control over the switched output at the output ports 74,76.

19 An analog time delay module 84 will now be described with reference to Figure 9. The time delay module 84 has a front face 86 in which are located a control input 88, a normally on output port 90, a normally off output port 92 and an output indicator lamp 94. A timer delay dial 96 and a range selector switch 98 are also located in the front face 86. The timer delay dial 96 consists of a continuously variable selector and the range selector 98 can be placed in one of three positions.

The time delay module 84 can accept a signal in its control input 88, in response to which it will set an operator adjustable delay before providing a control signal via one of two output ports 90,92. A range of delay periods are selectable, since the range selector 98 can be selected to one of seconds, minutes or hours. The timer delay dial 96 can be used to adjust the delay period continuously. The present embodiment of the invention allows for ranges of 0 to 300 seconds, 0.5 to minutes and 0.5 to 30 hours depending on the position of the range selector 98.

The time duration module 102 has a front face 104 in which are located a control input 106, normally on output port 108, normally off output port 110 and an output indicator lamp 112.

Furthermore, a timer duration dial 114 and a three position range selector 116 are also located in the front face 104 of the time duration module 102.

This module has a similar appearance to the time delay module 84. However, incoming control signals into the control input 106 are converted into operator settable output signal durations in selectable ranges from 0 to 30 hours. Thus any signal at the control input 106 will be converted into selectable and variable pulses. This is ideal for example for controlling a constant delivery pump in order to pump a known volume of fluid for delivery to a piece of laboratory equipment.

A sensor trigger module 118 is illustrated in Figure 11. The sensor trigger module 118 has a front face 120, having located therein a control input 122, a normally on output 124, a normally off output 126 and an output indicator lamp 128. Furthermore, a trigger level dial and a sensor socket 132 are also located in the front face 120.

The function of the sensor trigger module 118 is to interact with a transducer which might require a power source and which returns an analog signal proportional to the applied constraint measured. For example, pressure sensors, temperature sensors, (including thermocouples) flow sensors, weighing scales and strain gauges fit this 21 description. The sensor trigger module 118 provides a range of voltages at the sensor socket 132 typically required by common transducers and an operator settable trigger point (by means of the trigger level dial 130) so that a signal can be generated at the output ports 124, 126 when the transducer output received at the sensor socket 132 exceeds a certain value. This can be applied to the control of a heater, so that the heater is switched off when a certain temperature is reached. As with the previously described modules, the control input 122, can be used to provide an overriding control on the sensor to the module 118.

In particular, the voltages placed at the sensor socket 132 can include zero volts, plus or minus 5 volts, or plus or minus 12 volts, all rated at 200 milliamps.

A multifunction timer module 134 will now be described with reference to Figure 12. The multifunction timer module has a front face 136, in which is located a control input 138, a normally on output port 140 and normally off output port 142 and an output indicator lamp 144. Moreover, a digital LCD display is also located in the front face 136.

This timer module 134 combines the functions of the delay timer module 84 and the timer duration module 102.

Moreover, it has the precision of digital control. The 22 operator settable delay and/or duration is now precisely determined by selecting the number of seconds required in each case on the four digit LCD display 146. Function keys such as a PRG key, and SEL key and a down arrow key as illustrated are provided to allow the user to select the desired time and whether delay or duration timing is required. The unit can also be configured to be combine these times into sequential or repeating sequences of outputs at the output port 140,142. The time delay setting ranges can be set from 0 to 9999 seconds, 0 to 99 minutes and 0 to 99 hours.

With reference to Figure 13, a logic module 148 has a front face 150 in which are placed four input ports and four output ports. Two of the input ports 152 and 154 are arranged with two of the output ports 156 and 158, together with an associated output indicator lamp 160, and are interconnected with appropriate circuitry so that one of the output ports 158 has an output signal placed thereon which is a non-inverted "Exclusive OR" function of the input signals at the input ports 152,154. The other output port 156 has a signal which is the inverse of the output signal from the output port 158.

Similarly, input ports 162 and 164 are combined with appropriate circuitry so that input signals placed on those input ports 162,164 are combined according to an 23 "AND" operation, the non-inverted output of that operation being delivered to output port 168, an inverse of that output signal being placed on the output port 166. The output indicator lamp 170 is provided, being illuminated when the output signal on the non-inverted output port 168 is logic high. Similarly, the output indicator lamp 16 is illuminated when the output port 158 has a logic high signal thereon.

The logic module 148 enables the logical combination or subtraction of input signals, which when combined with inverting or non-inverting outputs provides the basic elements of event interaction and control. In combination with timer and switch modules, basic bench top process control can easily be achieved, without complex programming skills being necessary. Therefore, a laboratory technician with little experience of computer programming or control methods can devise an arrangement of modules which can perform the control function required. of course, other logic functions could also be provided if considered

appropriate.

The specific embodiment also contemplates the provision of a counter module (not illustrated) which is provided with a control input, an operator settable pulse count from 1 to 9999, pulse input connectors, a reset 24 switch, and normally on and normally off output ports with an output indicator lamp associated therewith. The counter module will count the number of pulses input during the time that the control input port is logic "on" and will provide an output when an operator settable level is exceeded.

Moreover, an alarm module can be contemplated which will cause an audible and/or visual alarm to be generated on provision of an input signal to a control port. An output signal could be used to power a system alarm system or could be linked in with existing systems. The audible signal could be volume controllable, and a variety of reset functions could be selectable. The alarm module could also interact with a pager so that a laboratory technician could be contacted if required.

An application of the modules described herein will now be described with reference to Figures 14 and 15.

In Figure 14, a system can be seen, having been constructed from a rack including a power supply 20, a mains control module 40, a timer duration module 102 and a switch module 68. The normally on output port 74 of the switch module 68 is connected to the control input 106 of the timer duration 102, and the normally on output 108 of the timer duration module is connected to the control input 44 of the main control module 40. With reference to Figure 15, the modules are shown in more schematic form. The combination of the modules is used to control a gravity feed affinity chromatography column.

In such a piece of equipment, there is a requirement that liquid be supplied to the top of the column so that it remains above an acceptable minimum level. Therefore, in Figure 15, the column 180 is illustrated with a widened upper end 182. A float switch 184 is provided in the widened upper end 182. The float switch 184 is closed when the liquid in the upper end 182 is above an acceptable minimum. Below that acceptable minimum, the float switch opens. A supply pipe 186 is arranged to supply liquid to the column 180, by means of a pump 188, a reservoir 190. A column exhausts liquid to a sump 192.

In use, when the liquid level drops below the acceptable minimum, the pump 188 is required to run until the level of the liquid rises and the float switch 184 closes again. The system operates by being configured to detect when the normally closed switch opens. At that point, the switch module 68 presents a control signal to the control input 106 of the timer duration module 102.

In accordance with the preset time set on the timer duration module a pulse is output from the timer duration module 102 to the control input 44 of the mains control module 40. The mains control module 40 is connected to 26 the pump 188 and so the pump 188 is operated for a set period of time in accordance with the timer duration module. In that way, by incorporating a timer duration into the control system, fluttering can be avoided which would otherwise take place if no timer duration module were used.

Referring now to Figure 16, a system for performing the same operation as that illustrated in Figure 14 but comprising modules according to a second specific embodiment is shown. Corresponding modules to those of Figure 14 are used, namely a base module 1020 and depending modules 1040,1102 and 1068. The depending modules include a control module 1040, in particular a 6 Amp AC mains output control module. Another of the depending modules is an intermediate module 1102, in particular an analog time delaying module. The third depending module 1068 is a sensor module, in particular a switch input sensor module.

Base module 1020 includes a main on/off switch 1028, a reset switch 1026 which corresponds to the reset switch 26 of power supply 20 illustrated in Figure 2. Base module 1020 also includes an on/off light 1029 which indicates if the base module is on and correctly outputting output power signals. Connecting cables 1010, 1011,1012 transfer the output power signals generated by 27 base module 1020 to each of depending modules 1040,1102, 1068 sequentially.

The 6 Amp AC output module 1040 includes a mains type socket 1046 adapted to receive a conventional mains plug; a control signal input socket 1044; inverted and non-inverted main signal output sockets 1043,1045; and inverted and non-inverted indicator lights 1049,1048.

The time duration intermediate module 1102 has a time duration dial 1114 which corresponds to the time duration dial 114 of the time duration module 102 of the first embodiment. Additionally, module 1102 has a control signal input socket 1088; inverted and non inverted main signal output sockets 1092,1090; and inverted and non-inverted indicator lights 1093,1094.

Switch input sensor module 1068 has a "normally open" or "normally closed" position switch 1082 external switch control signal input sockets 1080, modular control signal input socket 1072; inverting and non-inverting mains signal output sockets 1076,1074; and inverting and non-inverting indicator lights 1077,1078. A first single core control signal wire 1001 is connected between the non-inverting main signal control socket 1090 of the intermediate module 1102 and the control signal input socket 1044 of the control module 1040. A second single core control signal wire 1002 is connected between the 28 non-inverting main signal output socket 1074 of the sensor module 1068 and the control signal input socket 1088 of the intermediate module 1102.

operation of the system illustrated in Figure 16 is similar to that of the system illustrated in Figure 14 and described above. Thus, a f loat switch which is normally closed is connected between the external switch control signal input sockets 1080 and the position switch 1082 is set in the normally closed position. This causes the non-inverting main signal output socket 1074 to go high only when the f loat switch connected between sockets 1080 is opened. Note that the indicator lights 1077, 1078 are illuminated whenever the corresponding inverted or non-inverted mains signal output socket is set high.

Thus in the present case, while the f loat switch is closed inverting indicator light 1077 will be illuminated and non-inverting indicator light 1078 will be unilluminated.

When the logic high from the main signal output socket 1074 is communicated to the control signal input socket 1088 of the intermediate module 1102, the non inverting main signal output socket 1090 is caused to go high for a time duration which is determined by the position of the time duration dial 1114.

29 When the high voltage value produced by the non- inverting main signal output socket 1090 is communicated to the control signal input socket 1044 of the control module 1040 via control signal wire 1001, the mains signal output socket 1046 is connected to the AC mains voltage signal which is one of the output power signals generated by the base module 1020 and this mains signal is used to drive an external pump. Additionally, the non-inverting main signal output socket 1045 is caused to go high during this time and the corresponding non inverting indicator light 1048 is illuminated.

Referring now to Figure 17, the backs of modules 1020,1040,1102 and 1068 are illustrated. Note that in this second embodiment, no rack is provided for transferring power signals between modules. Instead, each module is free-standing with supporting legs 1300.

Base module 1020 is connected to the mains supply via a mains cable and plug 1340 and is adapted to generate seven output power signals which are communicated sequentially via cables 1010,1011,1012 to all of the depending modules 1040,1102,1068 stacked thereon. Each power signal cable 10 10, 10 11, 10 12 has two matching multi pin plugs 1310 at either end of the cable. one of these plugs 1310 is adapted to be plugged into a power output socket 1320 and the other plug 1310 is adapted to be plugged into a power input socket 1330 belonging to a module immediately on top of a module to whose power output socket the other end of the cable is connected.

Note that each depending module has both a power output socket 1320 and a power input socket 1330.

Referring now to Figure 18, there is shown a circuit diagram of the base module 1020. The mains cable 1340 includes earth, live and neutral lines. The earth line is stud bonded to the metal enclosure of the base module 1020 and earth connections are made from there to an overload circuit breaker and reset switch 1026, a power supply unit 1800 and power output socket 1320. The live and neutral lines of mains cable 1340 are connected via the overload circuit breaker and reset switch 1026 to the mains switch 1028 and from there both to the power supply unit 1800 and to the power output socket 1320. The power supply 1800 is adapted to generate a plurality of DC voltages namely a 24 volt DC voltage, a 12 volt DC voltage, a 5 volt DC voltage and a 0 volt DC voltage.

Wires between the power supply unit 1800 and the output power socket 1320 connect individual pins of the power output socket 1320 to the power supply unit to enable these DC voltages to be supplied to any of the depending modules.

31 Referring now to Figure 19, the wiring on each depending module connecting a depending module ' s input power socket 1330 with its corresponding output power socket 1320 comprises a printed circuit board 1900 in which a direct connection is made between each pin of the input power socket 1330 and the corresponding pin of the output power socket 1320.

Referring now to Figure 20, there is shown a circuit diagram of the 6 Amp AC control module 1040. Module 1040 receives earth, live, neutral, +5 volt DC and 0 volt DC power signals from its input power socket 1330 and is able to output via its live and neutral lines from its AC mains signal output socket 1046 up to 6 Amps of current at mains voltage. Additionally, module 1040 is adapted to output at its non-inverted 1045 and inverted 1043 main signal output sockets either +5 volts or 0 volts control voltage signals and is adapted to illuminate either the inverted indicator LED light 1049 or the non-inverted indicator LED light 1048 depending on whether the non inverted or inverted output socket is high respectively.

The module 1040 may be switched between a first state in which the mains output signal socket 1046 is disconnected from the mains supply, the inverted indicator LED light 1049 is illuminated and the inverted output socket 1043 is maintained at a logic "high,, of +5 volts; and a 32 second state in which the mains output signal socket 1046 is connected to the mains supply for outputting up to 6 Amps of mains voltage power, the non-inverted indicator LED light 1048 is illuminated and the non-inverted or normal output socket 1045 goes "high" at +5 volts. The module 1040 is switched between the first and second states in dependence on whether the control input socket 1044 receives a "low" i.e. 0 volt DC signal or a "high" i.e. 5 volt DC signal. When a low signal is communicated to the control input 1044 a first inverting driver 2021 receives a low and therefore outputs a high signal which is communicated directly to the inverting output socket 1043 as well as to the input of a second inverting driver 2022 whose output, which is therefore low, is communicated to the non-inverting output socket 1045.

The inverting indicator LED light 1049 is connected between a +5 volts rail and the non-inverting output socket 1045 while the non-inverting indicator LED light 1048 is connected between the +5 volt rail and the inverting output socket 1043. The output of the second inverting driver 2022 is connected to the inputs of third and fourth inverting drivers 2023, 2024 which respectively drive first and second relays 2010, 2011 which switch the neutral and live pins of the output socket 1046 into or out of connection with the 33 corresponding input live and neutral pins of the output power socket 1330. A thermal cut-out circuit breaker 2030 is connected in series with the relays 2010,2011 and will cut out if a significant amount of current over 6 Amps is drawn from the output socket 1046. A pull-down resistor 2040 ensures that the control input is maintained at 0 volts in the absence of any control input signal at the control input socket 1044. Pull-up resistors 2051,2052 are connected at the outputs of the first and second inverting drivers 2021,2022 to ensure that the voltage of these nodes is maintained at 5 volts unless the respective inverting driver is forcing a low voltage. Ferrite beads 2001,2002 and 2003 are placed on the wires leading to the sockets 1044,1043,1045 to impede unwanted high frequency noise signals appearing at these sockets.

When a high signal is received at the control input socket 1044, the first inverting driver 2021 outputs a low voltage signal which causes the inverted output socket 1043 to go low and the non-inverting indicator LED light 1048 to be illuminated. The low voltage output by the first non-inverting driver drives the second non inverting driver 2022 to go high which causes the non inverting output socket 1045 to go high and the inverting indicator LED light 1049 to be extinguished. The low 34 voltage generated by the second inverting driver 2022 causes the third and fourth inverting drivers 2023 and 2024 to go low. The output of the third and f ourth inverting drivers 2023 and 2024 is connected to the +5 volts rail via the relays 2010 and 2011. This causes current to flow through the relays 2010,2011 which causes them to connect the live and neutral pins of the mains signal output socket 1046 to the corresponding live and neutral pins of the input power socket 1330 thus permitting an external device connected to the mains signal output socket 1046 to be driven.

Referring now to Figure 21, there is shown a circuit diagram of the switch sensor module 1068. Switch sensor module 1068 only uses the +5 volt and 0 volt DC signals supplied to it by the power input socket 1330. The switch control input sockets 1080, which are adapted to be connected to an external switch which may either be open or closed, are connected to ground and to a pull-up resistor 2140 respectively. The node between the respective input switch socket and pull-up resistor 2140 is connected to a first terminal 1082a of position switch 1082 and to the input of a NOT gate 2021 whose output is connected to the second terminal 1082b of the position switch 1082. The output terminal 1082c of the position switch 1082 is connected to a first input of NAND gate 2023, the second input of NAND gate 2023 is connected to the output of a second NOT gate 2022 whose input is connected to control input socket 1072; in this way, whenever the control input socket 1072 receives a high signal a low signal will be communicated to the second input of the WAND gate 2023 causing the output of the NAND gate 2023 to be high regardless of the voltage supplied to the first input. The output of the NAND gate 2023 is connected both to the inverting output socket 1076 and via a third NOT gate 2024 to the non-inverting output socket 1074. Again, the non-inverting indicator LED light 1070 is connected between the +5 volt rail and the inverting output socket 1076, and the inverting indicator LED light 1077 is connected between the +5 volt rail and the normal output socket 1074. Various integrating capacitors are included in the circuit to smooth out unwanted high frequency signals in a conventional manner, and ferrite beads are connected to all wires leading to external sockets to impede unwanted high frequency noise picked up by the external sockets.

To ensure that the power connections between the modules are correctly made, each of the input power sockets 1330 may be configured as a male-type connector while each of the output power sockets 1320 may be configured as a female-type connector. The connecting 36 leads 1010 are provided at one of their respective ends with a male-type connector f or cooperating with the female-type output power sockets 1320, and at the other end with a f emale-type connector for cooperating with the male-type input power sockets 1330. By using such a connection scheme, it is ensured that an output power socket 1320 can only be connected to an input power socket 1330, and the situation wherein the exposed electrodes of a male-type connector become live is avoided.

Alternative arrangements of the modules of the present invention (so as to form alternative systems according to the present invention) are envisaged. For example, an arrangement comprising a counter intermediate module, a sensor module and a base module could be used for counting the number of occurrences of an event detected by the sensor module; in this arrangement no control module for controlling an external device is required. An arrangement comprising a sensor module, a control module and a base module could be used for directly controlling an external device in direct dependence upon the sensing of an external condition by the sensor module without requiring any intermediate processing; in this arrangement no intermediate module is required. An arrangement comprising a timer intermediate 37 module and a 230V AC output control module could be used to control an external device to operate for a predetermined period of time (without being responsive to any externally sensed conditions); in this arrangement no sensor module is required.

From the above described alternative arrangements, it is clear that a system according to the present invention may comprise any one of a large number of different combinations of modules. It is intended that the scope of the present invention should be determined solely in accordance with the appended claims.

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Claims (26)

CLAIMS:

1. A modular control system comprising a base module, and at least one dependent module, wherein:

the base module comprises power supply means having an input to receive power at a predetermined first voltage and a power output means to provide power at a plurality of predetermined output voltages; the dependent module comprises:

power input means for receiving each of said plurality of predetermined power supply output voltages provided by said base module; signal-input means for receiving an input signal; control means responsive to said input signal; and signal output means controlled by said first control means for providing an output signal at one of said plurality of predetermined output voltages.

2. A modular control system according to claim 1, wherein each dependent module further comprises power output means connected to said power input means for providing each of said plurality of predetermined power supply output voltages.

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3. A modular control system according to claim 1, wherein said power output means of said base module and said power input means and power output means of said dependent module are configured as multi-pin connectors.

4. A modular control system according to claim 3, wherein said multi-pin connectors are of cooperable male and female types, the power output means being configured as female-type connectors and the power input means being configured as male-type connectors.

5. A modular control system according to claim 4, further comprising a connection lead having at one of its ends a connector cooperable with the female-type connector of a power output means, and at its other end a male-type connector cooperable with a power input means.

6. A modular control system according to any preceding claim, wherein the signal input means of the dependent module is capable of receiving a signal from the signal output means of another dependent module.

7. A modular control system according to any of claims 1 to 6, wherein the signal output means of the dependent module is adapted to output a mains voltage power supply.

8. A modular control system according to any of claims 1 to 5, wherein the signal input means of the dependent module comprises a pair of terminals for connection to an external device.

9. A modular control system according to claim 8, wherein one of said pair of terminals is supplied with a voltage by the module, and the control means is responsive to a voltage detected at the other terminal.

10. A modular control system according to any of claims 1 to 5, wherein the signal input means of the dependent module is capable of receiving an input signal of varying characteristic.

11. A module for use in a modular control system, the module comprising; power input means for receiving a plurality of power supply voltages; signal input means for receiving an input signal; control means responsive to said input signal; and 41 signal output means controlled by said first control means for providing an output signal at one of said plurality of power supply voltages.

12. A module according to claim 11, further comprising power output means connected to said power input means for providing each of said plurality of power supply voltages.

13. A module according to claims 11 or 12, wherein the signal input means of the module is capable of receiving a signal from the signal output means of a second module.

14. A module according to claim 13, wherein the signal output means of the module is adapted to output a power supply signal for driving an external device, and the control means is a switching means.

15. A module according to claim 13, wherein the signal output means of the module is adapted to output a control signal applicable to the signal input means of a second module.

16. A module according to claim 15, wherein the control means comprises a delay circuit operable to control the 42 signal output means to provide an output signal a predetermined length of time af ter the module receives an input signal.

17. A module according to claim 15, wherein the control means comprises a timer circuit, and is operable to control the signal output means to provide an output signal for a predetermined length of time upon receipt of an input signal.

18. A module according to claim 15, wherein the signal input means comprises a plurality of signal input ports, and wherein the control means is operable to perform Boolean processing operations on the signal inputs and is operable to control the signal output in accordance with the result of said processing operations.

19. A module according to claim 18, wherein the Boolean processing operation is a logical "AND", "NAND", "XOR", or an "XNOR" operation.

20. A module according to claim 11, wherein the signal input means of the module is capable of receiving an input signal from an external device.

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21. A module according to claim 20, wherein the signal input means of the module comprises a pair of terminals for connection to an external device.

22. A module according to claim 21, wherein one of said pair of terminals is supplied with a voltage by the module, and the control means is responsive to a voltage detected at the other terminal.

23. A module according to any of claims 20 to 22, wherein the signal input means of the module is capable of receiving an input signal of varying characteristic.

24. A base module for use in a modular control system according to any of claims 1 to 10, substantially as herein described with reference to Figures 1, 2, 14 and or 16, 17 and 18.

25. A dependent module for use in a modular control system according to any of claims 1 to 10, substantially as herein described with reference to Figures 5 to 15 or 16, 17, 19, 20 and 21.

26. A modular control system substantially as herein described with reference to Figures 1 to 15 or 16 to 21.