GB2354909A - Controlling remote plant or machinery via a mobile telephone or satellite telephone transceiver - Google Patents

Abstract

In a control system for an agricultural diesel powered pumping station used for irrigation purposes, the pumping station 10 is provided with a mobile telephone 12 or satellite telephone transceiver. The telephone provides an output which is applied to a control unit 14 which detects control signals transmitted by telephone, and operates appropriate relays to control the pump. The system commands can be sent using Dual Tone Multi Frequency (DTMF) tones. Because it utilises existing cellular or satellite radio telemetry, the system allows equipment to be remotely operated anywhere where there is cellular telephone or satellite telephone coverage. The operator can also obtain information from the machine being operated by using the telephone link. For this the control unit 14 is programmed to transmit tone signals or recorded voice messages to the operator, for example, in response to predetermined codes received from the operator.

Description

2354909 METHOD AND APPARATUS FOR CONTROLLING REMOTE PLANT OR MACHINERY

Background of the invention

This invention relates to methods of and apparatus for controlling remote plant or machinery.

In order to remotely control machinery it has been proposed to set up a radio link to the machinery using a private radio network (PMR). This requires an infrastructure of radio masts and base stations to be constructed or hired, and it requires private mobile radio sets to be provided to the operators. Once the permanent infrastructure has been set up, the equipment can not be moved outside the range originally intended when it was constructed. In cases where line-of-sight microwave links are used, it may be impossible to move the equipment without reconfiguring the telemetry. In many cases the costs of this system are prohibitive.

The invention is particularly suitable for, but is not limited to, the operation of agricultural diesel powered irrigation pumping stations. The pumping stations are often mobile and often in isolated locations. Remote operation of the equipment would provide significant time savings for the operator.

Conventional remote control systems currently available would not be effective. They do not have the necessary range and require the operator to maintain attention on the machine in order move the correct controls. This is impossible because the operator is out of sight of the machine.

Summary of the invention

The invention in its various aspects is defined in the independent claims below, to which reference should now be made. Advantageous features of the invention are set forth in the appendant claims.

A preferred embodiment of the invention is described below in detail by way of example. Briefly, the preferred embodiment of the invention takes the form of a control system for an agricultural diesel powered pumping station used for irrigation purposes. The pumping station is provided with a mobile telephone or satellite telephone transceiver. The telephone provides an output which is applied to a control unit which detects control signals transmitted by telephone, and operates appropriate relays to control the plant, in this case the pump. In particular the pump can be started and stopped from any remote location by a telephoned command.

Because the invention utilises existing cellular or satellite radio telemetry, it allows equipment to be remotely operated anywhere where there is cellular telephone or satellite telephone coverage. The system is quick and highly cost-effective to set up and run. It is reliable in operation, and moving the equipment will not require existing radio telemetry links to be changed.

The system thus interfaces a mobile cellular or satellite telephone with the equipment being remotely operated, in order to control the physical movements and activities of the equipment. Conveniently the system commands can be sent using Dual Tone Multi Frequency (DTMF) tones and combinations thereof, which are decoded at the receiver at the pumping station. However the system could also operate using voice commands or other forms of data transmission. The commands may include commands which initiate a pre-programmed sequence.

In the past systems have been employed to obtain and send information, and to control bank accounts and various forms of answering machines, by using DTMF tones. In these systems the physical operation of plant and machinery is not controlled. At least the end of the link which receives the commands is also connected to the traditional landline telephone network.

By using the preferred system embodying the present invention it is also possible for the operator to obtain information from the machine being operated, by using telephones. To achieve this the equipment is programmed to transmit tone signals or recorded voice messages to the operator, for example, in response to predetermined codes received from the operator.

Most farm workers are equipped with a mobile telephone. The system therefore allows them to use equipment they already have to hand to operate and enquire on the operational status of the pumping station while they themselves are on foot and in another remote location.

The equipment can easily be used to operate any pumping station within agriculture or other industries. The principle of operating machinery using signals transmitted to a cellular telephone or satellite telephone could be adapted to operate other machines e.g. generators.

Brief description of the drawings

The preferred embodiment of the invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a block diagrammatic view showing a diesel-powered agricultural pumping station equipped with a remote control system embodying the invention; Figure 2 is a more detailed diagram of the tone receiver and decoder in the system of Figure 1; Figure 3 illustrates a relay forming the battery charging and isolation circuit in the system of Figure 2; Figure 4 illustrates other relays used in the control unit of Figure 2; Figure 5 is a schematic side view of the pumping station shown in Figure 1; Figure 6 (formed of Figure 6A and Figure 6B) is a block schematic wiring diagram for the junction/ control box used at the pumping station; and Figures 7 to 24 are timing diagrams illustrating the operation of software in the control unit.

Detailed description of the preferred embodiment

The embodiment of the invention illustrated in Figure I is used to control an irrigation pump 10 which is at a remote location of a farm or horticultural holding. The pump is provided with a mobile telephone 12 which is connected to the pump through a control unit 14. The control unit decodes or interprets commands received via the telephone 12 and includes relays to provide power to the pump to cause it to start and stop. Sensors on the pump 10 feed data back to the control unit and this can then be transmitted using the mobile telephone 12.

The telephone can be accessed from fixed or mobile telephones as shown. The user of a mobile telephone 20 can place a call to the telephone 12 at the pump through the existing mobile telephone network, diagrammatically illustrated at 22, and can then send commands to it. The user of a fixed telephone 24 connected to the public switched telephone network (PSTN) 26 can equally dial the mobile telephone, and the call will be routed through the mobile network in conventional manner. It will be appreciated that Figure 1 is very diagrammatic.

The system provides a form of robotic technology coupled with costeffective long-range radio remote control. A simple signal sent by radio can start the robotic pumping station on a programme that covers its entire operation, without further intervention from the operator. The controller 14 includes a Programmable Logic Controller (PLC) 30 which monitors and controls all the functions that a human operator would carry out.

The distances involved are too great for systems using infra-red devices or for short range radio devices of the type used to operate garage doors and car alarms.

The commands are transmitted in the form of DTMF tones.

Integrated circuits are available which encode and decode the DTMF codes. If a private radio network (PRN) were used it would be necessary to make use of a system utilising base stations and boosters in several locations around the farm. This is not a practical option because the pumps are often moved distances of up to 25 miles (40 km) between farms and the costs involved in covering all existing locations and potential future locations are prohibitive.

Even if such a system could be constructed it is possible that in some conditions the signal will still not be of is adequate quality.

By using mobile telephones these problem are overcome in any area where mobile telephones can be used. The transmission quality is good, especially where digital telephones are used. Consequently the system can be used in any of the necessary locations and does not require additional transmitting equipment to be provided to the operators.

The interfacing between the telephone and the machine being operated is carried out by a Dual Tone Multi Frequency (DTMF) receiver /decoder 32 within the control unit 14, and the construction of which is described in detail below. The controller also contains software within a (PLC) as will likewise be further described.

The DTMF re ce iver /decoder 32 converts analogue signals received from the telephone into a digital output, which is transmitted to the PLC 30. The PLC is programmed to act on these signals or combination of these signals in order to operate the machinery in question.

Referring to Figure 2, the DTMF receiver/decoder consists of a HT9170/HT9170A tone receiver manufactured by Holtech Semiconductor Inc., Taiwan. This provides integrated DTMF receiver and digital decoder functions.

Output from the tone receiver is passed through a 7406 buffer amplifier IC where it is amplified and inverted. Output from the 7406 is used to operate four internal relays Rl-R4, which switch a 24V dc supply provided externally from the PLC. Four outputs exit from the DTMF receiver/decoder, and return 24V dc to four data inputs of the PLC. These will either be high at 24V dc or be at 0 volts in various combinations depending on the tone received. This provides sufficient information to control the program being run by the PLC.

A fifth relay R5 is included in the tone receiver/decoder which is operated by the other four output relays. When the output relays are operated in the correct combination, being the output resulting from the DTMF tones corresponding to the number 1, the fifth relay is operated. This is used to operate a latching circuit at the control unit that provides power to the PLC. This relay also momentarily isolates the power supply of the tone receiver decoder and the telephone to ensure that it is free from electrical noise transmitted in the power supply from the voltage inverter while it is powering up.

It has been found that electrical noise can be introduced if an attempt is made to carry out this operation without the use of a fifth relay i.e. by passing current from the latching circuit directly through the data output relays. This causes the 7406 amplifier to lock up, requiring the device to be turned off before normal operation is resumed.

A 3.58mhz ceramic resonator XTAL as shown on Figure 2 provides frequency calibration.

The input signal to the receiver should be within +0.3V to -0.3V. However the output from the telephone may often be from an amplified circuit well in excess of this. It has been found that if this output is fed directly into the receiver, operation will be at best unreliable therefore a variable resistor is included in the circuit to allow the signal to be attenuated. This may be adjusted depending on the output received from various telephone devices the receiver is linked to.

LEDs have been linked in parallel with the output of the 7406 buffer amplifier and the data output relays. This provides a visual signal that the 7406 is operating correctly which is useful in fault diagnosis. Power supply to the I.C.s, is 5V dc and a semiconductor voltage regulator supplies this. Care must be taken to ensure that an adequate heat sink is provided because the voltage regulator will become extremely hot in operation. A decoupling capacitor is provided in the circuit between the voltage regulator and the DTMF receiver.

A diode is included in the power supply circuit to assist the decoupling capacitor and to prevent damage caused by accidentally reversing the polarity of the power supply.

The circuit is mounted within a PCB housing so that it may be mounted on a 35x7.5mm DIN rail with the other components. A 12 pin plug with screw terminals provides for easy electrical connection to the other components within the control unit 14.

The control unit contains a Programmable Logic Controller (PLC) which is under software control. Its operation will be described by reference to timing diagrams forming Figures 7 to 24 While the system is in stand-by mode, i.e. waiting for commands, the PLC is turned off in order to conserve battery power. As explained above, when the DTMF code for the number 1 is received, the DTMF decoder/ receiver turns the PLC on using a relay latching circuit 50 (Figure 4) in the control unit 14. When the PLC is turned on, it operates relay number 7 within the control unit 14, thus breaking the latching circuit and taking command of its own power supply. In order to avoid electrical noise causing the PLC to fail at this point there is a delay of 1.5 seconds (Figure 7 line 5 T019) to allow the capacitors within the PLC power supply to fully charge before the latching circuit is switched off.

With the latching circuit switched off, a timer within the PLC runs which will turn off the power supply if a valid start code is not received within one minute of power up (Figure 7 line la T001).

With reference to Figures 7 to 24, the start code is received as follows. The relevant inputs to the PLC from the DTMF receiver are X001 X006 X008 and XOOA (Figure 18).

These are switched by the output from the receiver as indicated in Table 1 at the end of this description. In the Table, H means high and L means low. These operate internal relays R051 to 59 and R040 to 42 (Figures 18 and 19). Relays R050 to 59 latch on once the tone has been is received and this latch will not be cancelled until either the correct number sequence has been entered or the star key is pressed which clears the system down by breaking the latch with R041, (Figure 19, line 3).

Figure 20 selects for a sequence of tones to occur in order to allow the start up routine to continue. Internal relay R068 is closed when R053 closes without R052 and R054 to 59 having been operated first (Figure 20 line 1), R069 closes when R057 is closed without R052 and R054 to 56 R058 and 59 having been closed first (Figure 20 line 2). R070 is closed when R059 is closed without first R052, R054to56 and R058 having been opened first (Figure 20 line 3). R068 to R070 latch on and when R042 is pressed R017 is closed (Figure 20 line 4) this in turn close R043 (Figure line 5) which will allow the rest of the programme to function. R017 also allows R060 to close (Figure 21 line 6) which breaks the latch on the pages 12 and 13 thus making the program ready to accept another code.

The programming to accept the stop code is in Figure 21. This operates in exactly the same principle.

In this way any combination of numbers can be used to control the program in the PLC. However with this particular program the same number may not be used more than once in any one code. For example 234 would be a valid code, however 224 would not. It is possible to Use the same numbers in different codes, for example 234 is different from 432 and both could be valid.

The above system can be used to add many codes and therefore many different commands to the machine. Those required in all cases will be start and stop. However codes could also be added to increase or decrease pressure, to hold pressure, or to make an enquiry into the status of the machine and receive a coded tone or voice message back. These will vary greatly depending on each individual application.

The hardware components will now be described.

The equipment referred to here as an irrigation pumping station may consist of mobile or fixed units. We are primarily concerned with the operation of mobile irrigation pumping station as shown in Figure 5. Typically such a pumping station consists of an internal combustion engine, particularly a diesel engine 4.1, connected by means of a rubber universal coupling 4.8 to an impeller pump. Both these are mounted to a road chassis 4.26 which can be trailed with a draw bar 4.27 from a tractor for transport.

In most applications the pumping station will be placed beside a ditch or reservoir from which it is intended to extract water for irrigation. The pump will draw water a height of up to 12 (3.6m) feet from the reservoir trough a suction hose of typically four or five inch (100 or 125mm) diameter. The water will then be pumped a distance of up to a mile to the irrigator through sectional aluminium. piping of 4 or 5 inch (100 or 125mm) diameter. Each section is approximately 18 feet (5.4m) in length.

The pumping station is equipped with the central process control unit 14 on Figure 1 which has already been referred to, a junction/operator interface 4.9, and various external valves and switches which vary according to application and the engine and pumping station used.

The control unit 14 and the operator interface are both manufactured from sealed mild steel enclosures.

Electrical wires connecting the two are carried within a conduit which connects to each unit using sealed 24pin and earth heavy duty connectors.

The control unit 14 is mounted anywhere on the pumping station where it is most protected from heat, water and impact damage, and in a location where it does not obstruct the normal operation of the station. The control unit is mounted on any point that is convenient for the operator. Components within the control unit 14 and operator interface are in general mounted on 35mm symmetrical DIN rails.

The central processor box houses a Toshiba M 20 PLC, 7 Omron R2 single pole 12Vcoil relays on DIN mount sockets, 2 Omron R" dual pole l2v coil relays on DIN mount sockets, a DTMF tone receiver /decoder as described above, a voltage inverter converting 12 to 110v, and a cellular satellite telephone with suitable power supply.

There are a number of external components collectively referred as devices, which either send information to the control unit 14 or are operated by it.

All these devices are connected to the junction/ operator interface. In many instances the type of external device may vary with specific application. They can be categorised into the following systems: priming, fuel and throttle management, engine monitoring, and pump performance monitoring.

With regard to priming the irrigation pumps in common use are the impeller type. These can not prime themselves and therefore are primed by the operator, typically using a diaphragm hand pump attached to the pumping station 4.23. This process may take up to 20 minutes and may have to be repeated every time the pump is stopped.

In order to allow the system to primed and help prevent loss of water from the system while it is not running, a one way valve known as a foot valve is fitted to the end of the suction hose that is kept below water.

This valve prevents the flow of water away from the pump back into the ditch but allows water to flow from the reservoir to the pump.

In order for the pumping station to start automatically it is essential that is reliably primed for every start up and that the engine cannot be started while the pump is not primed. The pump relies on the water passing through it to cool the bearings and water seals.

Therefore if the pump is run "dry", i.e. not properly primed and not drawing water, the bearings and water seals will overheat which will result in failure.

Because the engine cannot be run until the pump is primed, the only source of power to prime system is the 12 volt battery which is used to start the engine.

Because of the length of time that it can take to prime the system, the drain which electric pumping methods would put upon the batteries was a concern. Therefore the original ideas for self priming of the station employed the use of reservoir tanks which were to be filled once manually and then maintained filled by diverting some of the irrigation water. The tanks could be emptied into the system in order to prime the pump and suction hose. It was decided that the volume of water required would make these tanks too cumbersome for a mobile system, and thus it was decided that active electric pumping should be adopted.

Linking an electric motor to the diaphragm pump already mounted to the station was considered to be both cumbersome to convert to manual operation if required, and also be mechanically inefficient.

A submersible pump similar to a marine bilge pump was placed in the reservoir to prime the system through a small bore tube 4.24 introducing water at a point near the pump itself.

The experiments proved that electric pumping could be employed without causing any serious degradation of the battery's performance while starting the engine. However consideration must be given to ensure that the pump can lift the required head of water and survive a prolonged period of submersion. Alternatively a different type of electric pump capable of priming itself could be found. This type would not be required to stay under water and therefore may suffer fewer reliability problems.

The second priming method which can only be applied to underground mains systems is back feed. A by pass valve 4.22 and pipe 4.21 are fitted in the pipe line between the pipe and the pump exit casing bypassing the one way valve within the exit of the pump 4.28 which normally prevents is back flow of water in the main line. The by pass valve 4.22 is opened when priming is required allowing a small amount of water held in the mains to back flow into the pump 4.15 and suction pipe 4.20 priming the system. It has been found that when the system shuts down a sudden build up of pressure occurs on the exit side of the pump. This exceeds the normal running pressure of l0bar and it has been found that the bypass valve 4.22 can be damaged. It is necessary to fit a valve capable of withstanding pressures of 20bar in order that it will not fail in operation.

It was found that priming using both back flow and electrically pumped systems could occasionally be unreliable. It appeared that water flowed into the pump 4.15 apparently filling it. However once the engine 4.1 was started the pump 4.15 did not appear to be properly drawing water. The problem was normally solved by the manual operator pumping with the hand diaphragm pump 4.23 while the engine was running. This normally got water moving through the pump and once this had happened the system would pump normally.

In order to attempt to solve this a number of efforts were made to introduce water at different points in the system; however these had no effect. Different locations for the overflow were also tried however again these had no effect.

It appeared an air bubble was forming at the top of the pump, which because air was not being allowed to vent from the top of the pump could not be removed by introducing water into the system. This bubble caused cavitation in the pump reducing its efficiency and preventing water being drawn into it.

It was then discovered that the pump housings were normally made in two sections both of which already had a hole drilled and tapped to allow a drain plug to be fitted. It was discovered that one of the sections could be turned through 180 degrees giving a tapped hole for is venting at the top the pump and a hole for a drain plug at the bottom.

All systems have an air vent pipe 4.16 exiting from the top of the pump casing. This pipe is manufactured from hydraulic hosing and must be of sufficient specification to withstand pressures generated by the pump which will typically be a maximum of 14 Bar and a nominal running pressure of 10 Bar. It has been found that if this pipe is not fitted at the highest point of the pump is possible for air to remain trapped in the system thus preventing the pump from priming.

The air vent pipe 4. 16 passes to a mechanical one way valve 4.17 and electric solenoid valve 4.18 which operates at either 12 or 24V dc depending on application. The electrical solenoid valve will be normally closed (N/C or NC) so that when not in operation it prevents water passing along the vent pipe away from the pump. The mechanical one way valve 4.17 is fitted so that it will close to prevent the passage of air into the pump during manual suction priming. It has been found that without this valve it is impossible to manually prime the system. It is possible to replace this valve with a manually operated valve however it has been found that it is to easy for the operator to leave the valve in the wrong position thus preventing proper automatic operation.

A pipe exits from the electrical vent valve 4.18 into a small chamber 4.19 in which a float switch 4.24 is mounted. When water is introduced to prime the pump 4.15 it eventually overflows through vent pipe 4.16 and the open valves 4.17 and 4.18 to fill the chamber 4.19. The float switch is operated indicating that the system is primed.

The fuel system will now be described. A fuel and throttle management device consists of a throttle actuator and linkage and fuel Cut off. Typically there are two types of fuel cut of used by the system. Both types of cut off are designed to shut the engine off when they lose is power. The first type operates a valve within the fuel line. This is normally referred to as a fuel cut off valve 4.5. This valve is held open by electrical current and springs shut when the power is shut off. This valve 4.5 is simple in operation but tends to be slow in shutting off the engine because the engine will use the remaining fuel in the system before shut down. The second type of cut off is a rack pull device 4.6. This operates directly on the injection pump 4.4 and when power is cut off it pulls the distribution rack of the pump via a lever on the side of the injection pump. This causes the engine to shut down almost immediately.

The advantage of this method is the speed with which it operates the engine. However the disadvantage is that its electrical wiring is slightly more complicated and its electrical power consumption is higher. This is because the device consists of a spring loaded solenoid having two coils. The first coil referred to as the hold coil is capable of holding the solenoid against the action of the spring once it is in place but does not have the power to compress the return spring on its own. The second coil referred to as the energise coil is able to act with the hold coil to compress the spring brining the injection pump rack into the run position. Because of heat build up with in the device the energise coil can not operate for more that a few seconds at a time without becoming damaged.

S The throttle actuator consists of a slowly revolving motor which turns a threaded shaft along which a trunnion travels the trunnion is connected by means of cable to the throttle. A limit switch on the throttle actuator indicates when the throttle is at fully closed position.

Other types of throttle linkage exist which operate on similar lines.

The engine and pump performance monitoring will now be described. Various switch gauges may be used to monitor engine performance and are used in this device. The most common monitored functions are engine temperature 4.10, and oil pressure 4.11. Oil level and occasionally fuel level may also be monitored.

Pump performance is commonly monitored by a pressure gauge that reads the pressure of water exiting the pump 4.14. These normally have two moveable stops for high and low pressure so that pressure can be monitored to ensure it is within a set range. In addition to this a flow switch can be set into the system before the pump to give an indication that water is moving through the system.

On automatic operation power is supplied at 12v from the control /junction box 4.9 on the engine to connector 2 in the control unit 14. From here it is distributed to terminal 12 of the DTMF re ce iver /decoder, Telephone power and latching circuit relays 7, 8 and 9 (Figure 4) When on automatic standby only telephone and DTMF receiver/decoder are operating.

on receiving the start signal the DTMF receiver/de coder causes wire 33 to go to earth. This closes relay 7 which latches closed, and also closes the power supply from connector 2 to the rest of the control unit 14 viaconnector +12.

Power supplied at 12v from relay 7 via conneCtorS now turns on voltage inverter. Voltage inverter now supplies power at 240v ac to the PLC, which now runs.

On start up the PLC, after a delay of 1.5 seconds, wire 20 is switched to earth, which causes relay 8 to operate. This opens the latching circuit for relay 7 so that relay 7 now opens and power is no longer latched on, Relay 8 also closes the power circuit so that power continues to be supplied from connectors 2 to the +12v supply. The machine is now held on by the PLC and the PLC can switch it off by opening internal relay Y020 breaking wire 20's connection to earth. This deactivates relay 8.

The fuel cut off valve is supplied power from the +12v connector and opens when powered up allowing fuel to flow to the engine.

Op4erat on The operation of the system will now be described.

If X005 the throttle is not closed Y022 closes wire 22 to +12 which operates relay opening wire 40 to earth and closes wire 40 to +12v. Wire 40 is linked to connector 12 to umbilical 12 via umbilical connector terminal 12 to a N/C override switch and then to the negative terminal of the throttle actuator motor Diagram 5.

The motor reverses until the throttle is closed activating a limit switch, (Figure 6).

If the float chamber is empty then X009 (Appendix 1 Page 30) will be at 0 volts the PLC causes Y023 to close wire 23 to 12v this causes relay 5 to close supplying l2v to wire 80 to connector 13 to umbilical wire 13 to the prime valve pump relay within the junction box. The prime pump 4.25 now operates or depending on the fitment the vent valve 4.18 and prime inlet valve 4.27.

Operation of the float switch 4.24 by water filling the float chamber 4.19 through the vent valve 4.18 causes X009 to operate by supplying 24v to umbilical wire 9 to connector 9 to wire 9. Change in status of X009 causes priming to stop.

Change in status of X009 causes PLC to begin start sequence Y024 closes wire 24 to earth causing relay 6 to operate and the starter relay in the control junction box to operate. The starter relay supplies power to the starter motor. Relay 6 (Figure 3) also causes auxiliary battery charging circuit to open and the auxiliary battery to close to power to the Voltage inverter. In this way the voltage inverter is being run by the auxiliary battery during starting so that it is protected from voltage fluctuations occurring in the main circuit while the starter motor is running.

If the engine fails to start after ten seconds the PLC will reset to the priming sequence re prime and attempt a further start. Counter COO (Figure 10 line 5) will allow a further 7 start attempts before a fault condition is recognised.

When the engine starts the alternator relay in the Junction Operator interface operates causing status of XOOO to change. This causes PLC to stop starter motor (Figure 10 line 3).

operation of the starter and the alternator both override the priming sub routine so that the prime and vent valves cannot be open while the engine is starting or running (Figure 9 line 1) - If the engine stops within 30 seconds of starting the PLC shall attempt to restart. After 30 seconds a fault condition will be registered if the engine stops (Figure 10 line 6 TO04).

After a delay of 5 seconds (Figure 15 line 1 TO05) to allow normal build up of pressure the PLC monitors Water temp and oil pressure via relay 1 and 2 respectively. When either gauge reaches a failure condition a connection to earth is closed causing relays 1 or 2 to operate respectively. These will close wire 3 or wire 4 respectively to 24v switching X003 and X004 respectively.

Any fault condition will be retained in the PLC memory so that when switched on the condition is indicated to the operator by a combination of lights. The lights relate to the following faults: oil fault, low pressure fault, engine failed to start, water temperature fault, high pressure, engine stopped, prime fault, flow fault, and prime time-out.

If no fault condition has occurred the PLC will begin a sub routine to increase the pressure of the water being pumped during which time the throttle will be opened a small degree every 50 seconds (Figure 11 line 2 T006).

In order to open the throttle Y021 closes wire 21 to +12v operating relay 3 which opens wire 30 to earth and closes wire 30 to +12v wire 30 connects to connector 11 to is umbilical wire 11 which connects via the umbilical plug connector 11 to the positive terminal of the motor.

The Water pressure fault gauge is connected to the PLC via umbilical wire 7 to connector 7 to X007. The PLC will begin monitoring the Water pressure fault gauge after a period of approx. 20 minute or after the circuit is opened caused by the needle of the gauge lifting off its bottom stop.

The running pressure gauge is connected in the same manner by wire 6 via connector 6 to X002. When this connection closes the sub routine to increase pressure is halted.

At any point after the fault monitoring subroutine has been turned on the PLC will monitor for a closed circuit in the Water pressure fail gauge and if this appears on its own low pressure will be indicated.

Once running pressure is achieved which is indicated by the running pressure circuit remaining closed on its own The PLC will simply monitor for all fault conditions.

If any are detected it will open Y020 breaking wire 20 connection to earth this will cause the power relay 8 to operate so that the supply to +12 is broken. This will turn off the PLC and cut the power to the fuel valve which will close thus shutting down the engine if a fault is sensed.

Any fault condition will be stored in the memory of the PLC after it has been turned off. This will then be indicated to the operator by a combination of lights on the operator interface /junction box which will appear for a period of time when the machine is first turned on next turned on.

If an engine fault condition has been stored in the memory of the PLC this condition will block the programme from starting the engine until it has been cleared by pressing the stop button once.

The engine fault conditions are Low Oil, High temperature, or if the PLC senses that the engine has stopped on its own.

Water Pressure Fault conditions will indicate on the panel but will not block the programme from starting the engine. They clear automatically after a set period of time.

Allocation of inputs to the PLC L and N are 240/110v supply. Ground. Earthed to Voltage inverter.

LC and C are common together.

All inputs are operated by 24v which is supplied by the PLC.

XOOO is alternator input, X001 is a DTMF data input, X002 is the water at running pressure input, X003 is water temperature warning, X004 is oil pressure waning X005 is throttle closed limit switch, XOO 6 is a DTMF data input, X007 is water pressure warning, X008 is DTMF data input, X009 is prime indicator float switch, XOOA is DTMF data input and XOOB is all stop.

X003 and X004 are not switched directly by the input device. They are wired to relays which are in turn operated by their respective warning gauges. All other inputs are wired directly to the input device.

Output allocation.

In order to protect the internal relays of the PLC all outputs with the exception of Y026 and Y027 operate their respective devices via an external relay.

Y020 On/Off, Operates relay 8 providing power to the system while running. Y021 closes to move throttle forward. Y022 closes to move the throttle back. Y023 closes to operate the Energise coil of a solenoid operated rack pull type cut off (where fitted). Y024, closes to operate the starter. YO 25 closes to operate the priming pump or back flow vale depending on application.

Y026 and 27 both operate warning lights on the operator interface.

YO.20 and YO.24 are connected to earth.

is YO.21,YO.22,YO.23,YO.25 and CO are connected to the switched 12V dc supply.

Wire allocation and wiring of the PLC 110acv supply and ground connected directly to the voltage inverter power supply.

Wire 0 connects XOOO to connector 4.

Wire 1 connects X001 to DTMF decoder terminal 6.

Wire 2 connects X002 to terminal 6.

Wire 3 connects X003 to relay 1 Normally open terminal.

Wire 4 connects X004 to relay 2 normally open terminal.

Wire 5 connects X005 to connector 7.

Wire 6 connects X006 to the DTMF decoder terminal number 7.

Wire 7 connects X007 to connector 7.

Wire 8 connects X008 to the DTMF decoder terminal number 8.

Wire 9 connects X009 to connector 9.

Wire 91 connects XOOA to the DTMF decoder terminal number 9.

Wire 99 connects XOOB to connector 10.

connects Y020 to negative terminal or relay 8 coil.

Wire 21 connects Y021 to positive terminal of relay 3 coil.

Wire 22 connects Y022 to positive terminal of relay 4 coil.

Wire 23 connects Y023 to positive terminal or relay 5 coil.

Wire 25 connects Y025 to connector 60.

Umbilical wire 22 connects Y026 to warning light.

Umbilical wire 17 connects Y027 to second warning light.

Umbilical wire 16 connects Y020 to negative terminal of coil of starter relay in operator interface.

Umbilical wire 1 runs direct from +24V dc supply on the PLC and supplies power to sensors in the operator interface and on the engine.

Umbilical wire 2 links to connector 2 in the control unit 14 and provides 12V dc current to the control unit 14.

Umbilical wire 3 earths the control unit 14 to the engine/battery.

Umbilical wire 4 links to connector 4 and is alternator signal.

Umbilical wire 5 is not in use.

Umbilical wire 6 links to connector 6 and is water running pressure signal.

Umbilical wire 7 links to connector 7 and is water pressure fault signal.

Umbilical wire 8 links to connector 8 and is throttle closed signal.

Umbilical wire 9 links to connector 9 and is float chamber switch signal.

Umbilical wire 10 links to connector 10 and is all stop signal.

Umbilical wire 11 links to connector ii and is throttle forward power.

Umbilical wire 12 links to connector 12 and is throttle back power.

Umbilical wire 13 links to connector 13 and is energise fuel cut off coil power.

Umbilical wire 14 links direct to PLC Y025 and is prime pump on signal.

Umbilical wire 15 links to connector 15 and is hold coil power.

Umbilical wire 16 connects Y020 to negative terminal of coil of starter relay in operator interface.

Umbilical wire 17 connects Y027 to second warning light.

Umbilical wires 18 and 19 are not in use.

Umbilical wire 20 connects to Y024 on PLC and drops low to engage starter relay.

Umbilical wire 21 cold start power is not in use.

Umbilical wire 22 connects Y026 to warning light.

Umbilical wire 23 connects to coil negative terminal of relay 1.

Umbilical wire 24 connects to coil negative terminal of relay 2.

Relay allocation & function Relay I switches water temperature fault. Coil positive is 12v coil negative connected to temperature gauge by wire 23. Coil negative goes to earth on fault operating relay. Switched common contact connected to 24v supply from PLC. Switched NO contact is connected to PLC input X003 by wire 3.

Relay 2 switches Oil pressure fault and operates under the same principle as relay 1. The coil receives a 12cv supply. The coil negative terminal is connected to the pressure gauge and will earth on a pressure fault thus operating the relay. The switched common contact receives 24V dc from the PLC and the Normally open contact connects to X004 on the PLC via wire 4.

Relays 3 and 4 operate together to advance or retard the throttle motor. When neither relays are operated no power is supplied to the motor and both ends of the motor's windings are grounded to Ov. If an attempt is made to turn the motor an electromagnetic field is created within the winding resisting rotation. In this way the throttle mechanism is locked against accidental movement or creapage caused by vibration.

Relay 3 operates the throttle forward motion. The coil receives 12v from Y021 on the plc via wire 21. The negative side of the coil goes direct to 0 volts. The switched common connection is wired to the motor via wire 30 and 11 so that when positive the motor turns to advance the throttle. The normally open contact receives 12v so that when the relay operates to close the contact power is supplied to the motor. The normally closed contact goes to 0 volts so that when the relay is not operated the motor may reverse polarity and run to retard the throttle by that action or relay 4.

Relay 4 operates to retard the throttle on the same principle as relay 3.The coil receives 12v from Y022 on the plc via wire 22. The negative side of the coil goes direct to 0 volts. The switched common connection is wired to the motor via wire 40 and 12 so that when positive the motor turns to retard the throttle. The normally open contact receives 12v so that when the relay operates to close the contact power is supplied to the motor. The normally closed contact goes to 0 volts so that when the relay is not operated the motor may run on normal polarity advance the throttle by that action or relay 3.

Relay 5 is used to operate the energise coil if a rack pull type solenoid cut off switch has been fitted to the engine. Normally a warning buzzer is also connected to the same circuit as the energise coil. This provides an audible warning that the engine is about to start. The coil is powered by 12V dc received from Y023 of the PLC via wire 23. The negative terminal of the coil goes to 0 volts. The switched common connection is wired to 12V dc and the Normally open (NO) contact is connected to the device by wire 50 connector 13 and umbilical wire 13.

Relay 6 is a dual pole relay transferring power supply for the PLC itself from the main batteries to an auxiliary battery while the starter is turning. In this way power supply to the PLC is isolated from the voltage drop experienced by the main circuit while the starter is running. If the PLC were connected directly to the auxiliary battery it could not be turned off.

The negative terminal of the coil is connected to Y024 of the PLC via wire 24. The positive terminal of the is coil is connected to 12V dc via a diode which prevents operation of the coil by back currents from the manual circuit. The common connection No 4a is connected to the auxiliary battery and to the DTMF decoder. The normally closed connection 2a Receives the switched 12V dc supply through a diode. The diode prevents back charging of the main battery by the auxiliary battery. When not starting the auxiliary battery is being charged from the main switched 12V dc circuit. The normally closed contact No 2 Receives power from the switched 12V dc circuit. The common connection number 4 is connected to the voltage inverter which powers the PLC. The PLC is thus switched on and off with the switched 12V dc circuit.

When starting both common terminals are connected by switching to terminals 3a and 3 which are wired together.

The voltage inverter is now isolated from the main circuit but still kept powered by the auxiliary battery.

Relays 7 and 8 operate together both to temporarily latch the power on during power up and then to maintain power after power up. This latching action is necessary because electrical noise created during power up can degrade the signal received by the DTMF encoder. As a result of this the decoder can switch on and off very rapidly. This often occurs before the PLC has powered up and before Y020 has operated to hold the power on. Without the latching circuit it is extremely difficult for the machine to power up.

-5 Relay 7 is the latching relay and the latch is broken when relay 8 is operated by the PLC. The negative terminal of the coil of relay 7 is connected to the DTMF decoder via wire 33. This will be switched to earth by the DTMF decoder when the appropriate DTMF signal is received to initiate power up. The positive terminal of the coil is connected via a diode to the main unswitched 12V dc supply. The negative terminal of the coil of relay 7 is also connected to common terminal number 4. the Normally open terminal number 3 is connector to earth via relay 8.

When relay 7 operates the connection closes and thus the relay is latched on. The common terminal number 4a is connected to the main 12V dc power the normally open terminal number 3a provides switched supply to the rest of the system at 12V dc. this connection closes so that the rest of the system is powered up.

The negative terminal of the coil of relay 8 is connected to the PLC Y020 via wire 20 the positive terminal is common with the positive terminal of relay 7 the common terminal number 4 is connected to terminal 3 on relay 7 while the normally closed terminal number 2 on relay 8 is connected to earth. In this way when relay 8 is operated by the PLC after power up the latch is broken.

The common terminal 4a on relay 8 is connected to the main 12V dc power supply. The normally open terminal number 3a provides switched power at 12V dc to the rest of the system. When relay 8 operates power supply to the system is transferred from relay 7 to relay 8. Thus the PLC now holds power on and at any point can shut itself and the system down by operation of Y020.

Junction/Operator interface description

This is mounted on the pumping station within easy reach of the operator. Its purpose is to provide a control interface between the machine and the operator, to act an electrical junction box. To house the throttle actuator and to house a system of relays to operate the machine manually in the event of failure or disconnection from the control unit 14.

It is manufactured from a mild steel enclosure sealed to IP55 internal components are mounted on standard 35mm symmetrical DIN mounting rail. External lights and switches are mounted in the door of the enclosure. All cables to external devices exit from the bottom of the box via nylon glands sealed to IP68. The umbilical cable is connects to a heavy duty 24 pin plus earth connector in the bottom of the box sealed to IP55.

The throttle actuator is housed within the box. The throttle actuator turn handle exits one side of the box and is sealed against ingress of water using mastic sealant. The throttle cable exits at the opposite side of the box to the turn handle through a nylon gland.

Internal relay specification

Relays 1 and 4 are Omron G2 12V Coil dual pole relays. Relay 2, 3, and 5 are Similar Omron single pole relays. Relay 6 is a finder 12V dc coil relay with contacts rated at 20A @ 24V dc.

Junction /operator interface Internal relay allocation Relay 1 operates the bypass valve or priming pump dependant upon particular application of the pumping station.

When operating the bypass valve the relay is of the two-pole type, however if a pump is fitted the relay need only be single pole. The relay also operates the overflow valve so that overflow valve and pump operate together from only one output of the PLC.

The coil positive is connected to wire 14 and coil negative to earth.

First set of.poles common is unswitched 12V dc supply. NO contact is connected to wire 35 this will go high to open the bypass valve. Wire 52 is also linked to this contact and will go high to open the overflow valve.

The Normally closed contact is connected to wire 36 this goes to 12V dc to close the valve. When the coil is not operating the valve will close. This ensures that the valve will remain closed even when the control unit 14 is disconnected.

The common for the second set of poles is connected to earth. NO contact is connected to wire 37 and is earthed for the overflow valve when opening. Wire 53 which is earth for the overflow valve also connects to the NO contact The NC contact is connected to wire 38 and is earthed for the bypass valve when closing.

If a priming pump is being used in place of the overflow valve the pump motor positive will connect to the NO contact. The negative may go directly to earth. The overflow valve positive may connect to the NO contact and negative directly to earth. The common contact will be constant 12V dc supply.

In some applications the operator may wish to operate the valves manually. This can be done by providing an extra switch on the panel to operate the coil. This switch should be connected to the manual automatic change over so that the pump can only be operated manually while the pumping station is in Manual mode.

Relays 2 and 3 form the Fuel cut off latch in manual operation mode only.

When the system is switched to manual operation power is distributed to the fuel cut off latch circuit form the change over switch on the panel via wire 40. Wire 40 connects to the positive terminal of the coil of relay 2.

The negative terminal connects to connectors 2 and 3 and via a diode to wire 46 the Murphy gauge needle. The common closed contact of relay 2 is connected via wire 42 to the positive side of the coil of relay 3 and also to the override switch on the panel. The normally closed contact of relay 2 is connected to the cut off switch on the operating panel by wire 41 and to the fuel cut of coil by wire 55. The negative side of the coil of relay 3 is connected to earth. The common contact receives power at 12V dc from wire 40. The normally open contact is linked to the cut of switch on the panel via wire 43.

The fuel cut of latch circuit operates as follows operates as follows. Relay 3 switches power to the fuel cut off coil while relay 2 switches relay 3 and is operated by the fault condition in the gauges earthing the coil. When a fault condition is not present power is supplied to the coil of relay 3 by passing through the normally closed contacts of relay 2 thus holding the normally open contacts of relay 3 closed and maintain power to the circuit. Power is also supplied to the fuel cut off valve from the normally open contacts of relay 3. This latch can be broken in two ways. First the cut of switch can be operated breaking the connection between wire 41 and 43 thus preventing power being received by either the fuel cut off coil or the coil of relay 3. Secondly the coil of relay two may be earthed via the fault gauges if a fault condition is present. This will cause relay 2 to operate and break the connection of wire 41 to wire 42 thus preventing power being supplied to the coil of relay 3 thus breaking the connection between wire 40 and 43 and thus preventing power being received by the fuel cut off coil which will cause the cut off to spring shut.

If required the cut off may be manually overridden by operating the override switch on the operating panel. This will close the Normally open connection connecting between 29 - wire 40 and 42 thus supplying power direct to the coil of relay 3 and bypassing the cut off circuit.

Relay 4 is responsible for switching the Murphy gauge outputs between the manual and the automatic systems. The use of these relay minimises the use of further relays within the control unit 14 by changing the operating voltage of the fault gauges concerned from 12 to 24V dc depending on weather the system is being operated manually or automatically. This is only possible on the Murphy pressure gauges because unlike the other fault gauges they are not designed to earth through the case to the chassis of the pumping station.

When the system is switched to manual power is supplied to the coil of the relay via wire 40. The negative terminal of the coil is connected to earth. The common contacts of the first set of poles of the relay are connected to the Murphy gauge fault stop. The Normally closed contact is connected to the control unit 14 via wire 6. The normally open contact is connected to earth.

The common contact of the second set o poles of the relay are connected to the Murphy run pressure stop by wire 48 the normally closed contact connects to the control unit 14 via wire 7 and the normally closed contact is also connected to earth. While in automatic operation the needles of both gauges receive 24V dc via wire 46 which connects to wire 1 at the common terminal of relay 5. In manual operation power is not supplied by wirel and therefore power is supplied at 12V dc from wire 40 and passes through a diode connected to the common terminal of relay 5.

Relay 5 is connected to the alternator warning circuit and when in automatic mode provides an indication to the control unit 14 that the engine is running. When the system is on the positive terminal receives power at the engine voltage being either 24V dc or 12V dc depending on application via wire 28. The negative terminal of the coil is connected both to the warning light on the panel by wire 26 and to the alternator warning output by wire 27. The common pole of the relay receives 24V dc from the control unit 14 via wire 1 the normally closed contact is linked to the control unit 14 via wire 4.

When the engine is not running and the alternator is therefore not charging wire 27 earthed via the alternator.

The coil of relay 5 is therefore energised breaking the connection between wire 1 and wire 4. When the engine is running and the alternator charging power at engine voltage being 24 or 12V dc flows to wire 27 thus preventing the coil from energising. The connection between wire I and wire 4 is therefore made.

Relay number 6 starter relay. When the system is turned on in either manual or automatic mode power is supplied to the positive terminal of the coil of relay 5 from the switch in the operating panel by wire 33. The negative terminal of the coil is connected in parallel to both the normally open start switch on the operating panel via wire 50 and to the control unit 14 via wire 20.

The common contact of the relay receives power direct from the engine's batteries at either 12V dc or 24V dc depending on application. This supply is unswitched and will be fed to the system by wire 54 via a suitable in line fuse to connector 4 from where the power supply is fed to the relay and via wire 54 to the master switch in the panel. The normally open contact of the relay connects to the starter motor via wire 32 and simply provides power to the motor when the relay is operated by the action of either the switch on the panel or the switching within the control unit 14 causing either wire 50 or wire 20 to connect to earth.

Junction box/operator interface wire allocations Wires connected to the connection between the junction/operation panel and the umbilical are wired in the same sequence as the umbilical wire in order to allow easy connection and assembly.

Wire 1 provides power at 24V dc form the low amp supply on the PLC within the control unit 14. It connects umbilical wire 1 to the power distribution connector 1.

Wire 2 provides power at 12V dc to the control unit 14 for automatic operation. This connects the master switch on the panel to umbilical wire 2.

Wire 3 is earth for the control unit 14 and connects umbilical wire 3 to the earth point in the Junction/operator interface.

Wire 4 provides 24V dc to the control unit 14 to indicate that the engine is running and connects umbilical wire 4 to common terminal of relay 5.

Wire 6 provides 24V dc to the control unit 14 to indicate a water pressure fault and connects umbilical wire 6 to relay 4 normally closed contact.

Wire 7 provides 24V dc to the control unit 14 to indicate that the water pressure is at the required running pressure and connects umbilical wire 7 to relay 4.

Wire 8 provides 24V dc top the control unit 14 when the throttle closed limit switch is activated by the throttle returning to the fully closed position. Wire 8 connects umbilical wire 8 directly to the limit switch on the throttle actuator.

Wire 9 provides 24V dc to the control unit 14 indicating that the float switch has been closed by the level of water rising within the floatchamber. Wire 9 links the umbilical wire 8 directly to the float switch.

Wire 10 Provides 24V dc to the control unit 14 to indicate that the system is to stop. Links umbilical wire 10 directly to the No stop switch on the control panel.

Wire 11 provide 12V dc to the throttle motor for forward rotation of the motor and provides and earth for reverse rotation of the throttle motor. Connects umbilical wire 11 direct to the normally positive terminal of the motor.

Wire 12 provides 21V dc to the throttle motor for reverse rotation of the motor and provides an earth for forward rotation of the motor. Wire 12 connects umbilical wire 12 direct to the normally negative connection of the throttle motor.

wire 13 Provides 12V dc to the energise coil of a rack pull solenoid type cut off. This connects umbilical wire 13 direct to the device. This is only in use on systems with rack pull cut offs.

is Wire 14 Provides 12V dc to power the coil of relay 1 in order to operate the prime pump or valve. Connects umbilical wire 1 to relay 1 coil positive terminal.

Wire 15 provides 12V dc from the control unit 14 to the hold coil of a rack pull type cut off or to the coil of a fuel valve type cut off in order to maintain fuel supply to the engine while it is running. This connects umbilical wire 15 to the normally open terminal of relay3.

Wire 16 when the system is in automatic operation provides an earth to the control unit 14 latching the system on. Connects umbilical wire 16 to the normally open start switch on the control panel.

Wire 17 connects umbilical wore 17 Ro the panel warning light.

Wire 20 provides an earth for the coil of relay number 6 (starter relay) in order to operate the starter when in automatic operation. Connects umbilical wire 20 direct to the negative coil terminal of relay 6.

Wire 22 connects umbilical wire 22 direct to the panel warning light.

Wire 23 Earths on a temperature fault condition.

Connects umbilical wire 23 to connector 2 and then to wire 44 which is connected to the temperature gauge.

Wire 24 earths on an oil pressure fault and connects umbilical wire 24 to connector 3 and hence to wire 45 which terminates at the temperature fault gauge.

Wire 26 connects wire 27 to alternator warning light on panel. Connects with wire 2? at negative terminal of coil of relay 5.

Wire 27 Alternator warning, connects alternator warning light terminal to negative terminal of coil of relay 5. Goes to 12V dc when alternator is charging. Goes to earth when not charging.

Wire 28 switched supply at engine voltage either 24V dc or 12V dc depending on application. Connects relay 5 coil positive terminal to master switch.

Wire 32 Supply to starter motor provides 12V dc or 24V dc current to starter motor. Connects relay 6 normally open contact to starter motor. In some applications a connector number 4 is necessary to make wiring easier.

Both wires entering the connector from the relay and exiting the connector to the starter motor are designated 32.

Wire 35 power supply to bypass valve or priming pump.

Supplies positive 12V dc when pump is opening. Connects pump/valve to relay 1 Normally open contact.

Wire 36 supplies power to the bypass valve in order to close the valve. Connects bypass valve with relay 1 normally closed contact.

Wire 37 Earth to the bypass valve while opening or to the priming pump while priming. Connects valve or priming pump to normally open contact of second set of poles of relay 5.

Wire 38 Earth to the bypass valve while closing.

Connects bypass valve to normally closed contact of second set of poles of relay 5.

Wire 39 For use only in systems with manual priming option connects relay 1 coil positive terminal to a normally open switch on the control panel.

34 - Wire 40 supplies power at 12V dc while on manual operation mode. Connects master power switch on the panel to relay 2 coil positive and is then linked by a diode to relay 3 common terminal and to relay 4 coil positive.

Wire 41 Latch connection in cut off latching circuit, carrying power to both shut off valve/solenoid and to relay 3 coil via normally closed contacts of relay 2.

Connects the normally closed shut off switch on the panel to the normally closed contact of relay 2.

Wire 42 is the fault condition override link connects the common contact of relay 3 with the coil positive contact of relay 3 via a normally open switch on the panel. When the switch is closed the coil of relay 3 is energised causing power to flow to the cut off valve solenoid.

Wire 43 is the link from relay 3 to the cut off normally closed switch on the panel. At the cut off normally closed switch it connects with wire 41. This connection is broken by operating the switch in order to break the latch circuit and cut off the fuel supply.

* connects relay 3 Normally open contact to the normally closed cut of switch.

Wire 44 Temperature Fault, earths on fault condition.

Connects temperature gauge needle to connector 2.

Wire 45 Oil Pressure Fault, earths on fault condition. Connects Oil pressure gauge needle to connector 3.

Wire 46 Water Pressure gauges supply voltage at 12V dc or 24V dc. Connects needles of both water pressure fault gauge and the water pressure run gauge to the common contact terminal of relay 5 where it links to the 24V dc supply from wire 12 or receives a 12V dc supply from connector 2.

Wire 48 Run stop. In automatic operation Goes to 24V dc when the desired run pressure is reached. In manual operation provides an earth for the gauge. Connects the water running pressure stop to the relay second pole common contact.

Wire 49 Water pressure fault stop. Goes to 24V dc when a fault condition is reached. In manual operation provides an earth for the gauge. Connects water pressure fault stops to relay 4 first pole common contact.

Wire 50 on manual starting this goes to earth. Links relay 6 (starter) coil negative to the normally open start switch on the panel. When this switch is operated it closes the connection to earth thus allowing the coil of relay 6 to energise.

Wire 52 provides power supply to open overflow valve. Connects relay 1 First set of poles Normally open contact to overflow valve.

is Wire 53 Provides earth for the overflow valve connecting the valve to relay 1 normally open contact on the second set of poles.

Wire 54 Main power supply at either 12V dc or 24V dc dependant on wire application. For ease of construction after entering the box this is connected to connected to terminal block 4 and a second wire 54 connects terminal block 4 to the power distribution switch on the control panel. A link is also made between terminal block 4 and relay 6 (starter) common contact. This link is also designated wire S4.

Wire 55 Provides power to hold the shut off valve open or hold a rack pull shut off device in the open position. Connects relay 2 normally closed contact to the device. For ease of construction the connection may be made via terminal block 5.

While the invention has been described in the context of the remote control of an agricultural irrigation pump, it could be employed in many other applications where control of remote plant or machinery is required. For example it could be used to control the bilge pump on a yacht. Also many modifications can be made to the details of the equipment described, within the scope of the appended claims.

TABLE I

DTMF Receiver/Decoder output table Sorted in order External Pin out Pin out (IC) External Pin out Pin out 9 8 7 6 6 7 8 9 Wire allocation 91 8 6 1 14 13 12 11 1 6 8 91 XOOAj PLC Input XOOA X008 X006 XOOI D3 D2 D1 DO X001 X006 X008 Trans- 1 H H H L L L L H L H H H mission 2 H H L H L L H L H L H H 3 H H L L L L H H L L H H 4 H L H H L H L L H H L H H L H L L H L H L H L H 6 H L L H L H H L H L L H 7 H L L L L H H H L L L H 8 L H H H H L L L H H H L 9 L H H L H L L H L H H L 0 L H L H H L H L H L H L L H L L H L H H L L H L # L L H H H H L L H H L L A L L H L H H L H L H L L B L L L H H H H L H L L L C L L L L H H H H L L L L D H H H H L L L L H H H I H I 1, __1 I 38 -

Claims (24)

1 A method of controlling from a first location remote plant or machinery located at a second location, the method comprising the steps Of:

providing a mobile or satellite telephone receiver at the second location; providing a control unit coupled between the telephone receiver and the plant or machinery being controlled; telephoning the telephone at the second location from fixed or mobile telephone at the first location to form telephone link; sending commands over the telephone link from the first location to the second location; and is at the second location automatically interpreting the commands received over the telephone link, and automatically controlling the plant or machinery in accordance with the interpreted commands.

2. A method according to claim 1, in which the plant or machinery is agricultural plant or machinery.

3. A method according to claim 1, in which the plant or machinery is mobile.

4. A method according to claim 1, in which the plant or machinery comprises a pump.

S. A method according to claim 1, in which the plant or machinery comprises an internal combustion engine.

6. A method according to claim 1, in which the commands include commands to commence and stop operation of the plant or machinery.

7. A method according to claim 1, in which the commands are sent in the form of DTMF codes.

8. A method according to claim 1, in which the commands are sent in the form of voice commands.

9. A method according to claim 1, in which the commands are sent in the form of digital codes.

10. A method according to claim 1, in which information is sent over the telephone link from the second location to the first location.

11. A method according to claim 10, in which the information comprises information concerning the condition of the plant or machinery.

12. Apparatus for use in the method of claim I for controlling from a first location remote plant or is machinery located at a second location, the apparatus comprising:

a mobile or satellite telephone receiver at the second location; a control unit coupled between the telephone receiver and the plant or machinery being controlled, the control unit including:

means coupled to the telephone receiver for receiving commands over a telephone link from the first location; means coupled to the means for receiving commands for automatically interpreting the commands received over the telephone link; and means for automatically controlling the plant or machinery in accordance with the interpreted commands.

13. Apparatus according to claim 12, in which the plant or machinery is agricultural plant or machinery.

14. Apparatus according to claim 12, in which the plant or machinery is mobile.

15. Apparatus according to claim 12, in which the plant or machinery comprises a pump.

16. Apparatus according to claim 12, in which the plant or machinery comprises an internal combustion engine.

17. Apparatus according to claim 12, in which the commands include commands to commence and stop operation of the plant or machinery.

18. Apparatus according to claim 12, in which the commands are sent in the form of DTMF codes.

19. Apparatus according to claim 12, in which the is commands are sent in the form of voice commands.

20. Apparatus according to claim 12, in which the commands are sent in the form of digital codes.

21. Apparatus according to claim 12, in which information is sent over the telephone link from the second location to the first location.

22. Apparatus according to claim 21, in which the information comprises information concerning the condition of the plant or machinery.

23. A method of controlling from a first location remote plant or machinery located at a second location, substantially as herein described with reference to the drawings.

24. Apparatus for controlling from a first location remote plant or machinery located at a second location, substantially as herein described with reference to the drawings.