Field of the Invention

This invention relates to level switches and in particular, though not necessarily solely, to vibrating fork level switches used to detect moving

interface levels in tanks and the like.

Background of the Invention

Existing level switches do not commonly have a communications interface which is accessible after assembly of the switch. This can make it difficult or even impossible to configure, interrogate or test the switch in the field and even in the factory before despatch.

In some examples of level switch a limited degree of configuration is possible using one or more mechanical selectors incorporated in the switch, but these add cost, complication and potential unreliability to the switch, and are often difficult to access without opening the switch enclosure.

It is an object of this invention to provide a level switch that will go at least some way to addressing the aforementioned drawbacks; or which will at least provide a novel and useful choice.

Summary of the Invention

Accordingly the invention provides a level switch having a sensor and processing circuitry, said switch being characterised in that it incorporates a near field communication facility operable to communicate with a near field communication reader brought within an operating range of said facility, said near field communication facility and said processing circuitry being energisable from said reader.

Preferably said sensor is further energisable from said reader. Preferably said near field communication facility is configured to exchange data between said reader and said processing circuitry.

Preferably said near field communication facility is configured to communicate calibration data relating to said switch.

Preferably said near field communication facility is configured to

communicate diagnostic data from said switch.

Preferably said near field communication facility is configured to allow some control over functionality of said switch.

Preferably said functionality includes self-test functionality and/or licensed functionality. Preferably said facility and said reader further includes an access control facility configured and operable to limit access there-between.

Many variations in the way the invention may be performed will present themselves to those skilled in the art, upon reading the following description. The description should not be regarded as limiting but rather as an illustration, only, of one manner of performing the invention. Where appropriate any element or component should be taken as including any or all equivalents thereof whether or not specifically mentioned. Brief Description of the Drawings

The invention will now be described with reference to the accompanying drawings in which:

Figure 1 : shows an exaggerated schematic view of a level switch

according to the invention installed in a tank; and

Figure 2: shows, diagrammatically, the functional elements of a level switch according to the invention.

Detailed Description of Working Embodiments

Referring firstly to Figure 1 a level switch, in this case a vibrating fork point level switch 5, is mounted in a tank 6 in the conventional manner to monitor changes in medium in the tank, in this case indicated by the position of air/liquid interface 7. As is well known, when the level of interface 7 comes into contact with the switch 5, the frequency of vibration of the switch changes, and this change of frequency is typically used to effect a switching operation.

It must be stressed that Figure 1 shows the switch 5 mounted in an operating position for the purposes of illustration only. It will evident from the description which follows that significant benefits may arise from this invention well before the switch is put into use.

Turning now to Figure 2, the switch 5 conventionally includes a sensor 10 which senses a frequency change and communicates this to a processor 11 via a sensor interface 12. The processor 11 determines if the frequency change is of significance and, if so, generates a switching output at 13. The sensor 10 is, in this case, the fork. The remainder of the components 11, 12 and 13 are conveniently mounted within housing 15 from which the fork projects but which, in use, is on the exterior of tank 6.

A characteristic feature of this invention is that the switch 5 is provided with a near field communication (NFC) facility that is indicated generally at 15 in Figure 2. The NFC facility communicates with reader 16, when the reader is brought within the range of the NFC facility (typically within about 100 mm) allowing commands to be relayed to the switch and data to be transferred between the reader 16 and the switch 5. The communication facility is preferably configured to be passive, that is to say power to operate the facility is induced from the reader. Sufficient power is available to energise the sensor and the processor 11 of a typical level switch (up to 5mA @ 3.3 volts) but, during operation of the communication facility, the output 13 may be disabled. In the form shown the facility 15 includes an antenna 17 which communicates with an antenna 18 on the reader, the antennae 17 & 18 preferably acting as an air-cored transformer. Signals and power received by antenna 17 are communicated to an NFC processing chip 19 which, in turn, powers the processor 11 and interface 12; and also communicates data to and from the processor 11. Both the antenna 17 and the chip 19 can be mounted on the switch circuit board along with the operating components 11, 12 & 13 as described above. Typically both power and data can be transmitted through the housing 15, providing the housing is not formed from a conductive metal.

The reader 16 can, for example, be a computer, a dedicated device or a handheld device such as a mobile telephone, many of which are equipped with communications functionality. The combination of communications facility 15 and reader 16 allows a number of useful data transfers to be effected including some or all of the following:

1. Calibration data may be applied to and read from the switch 5, both in 5 the field and in the factory;

2. Specific product information such as serial numbers, other identity data and approvals information may be read to and from the switch, even in the factory, boxed, and waiting to be despatched;

3. The operating characteristics of the switch can be set for a particular 10 field application and can be altered in the field to fine tune

performance having regard to switching point and temperature parameters;

4. A functionality test may be invoked in the field and the results of that test accessed; 5. Data enabling or dis-enabling specific instructions; special and/or

additional functionality such as self-testing and enabling functions only available to users having an appropriate licence.

The switch may also include an access control facility to prevent unauthorised interference with the switch functionality. It will be appreciated that, using the present invention, all of the above can be achieved without opening the housing 15, without the need to incorporate any form of mechanical adjustment, and while the switch 5 is unpowered.