Patent Application
20100262843
The invention relates to data transfer in field devices. In particular, the invention relates to a control device for a field device for energy-controlled data transfer to an external receiver; to a field device comprising a control device; to a method for energy-controlled data transfer from a field device to an external receiver; to a program element and to a computer-readable medium.
Field devices often transmit the measured values acquired by them in a time-controlled, event-controlled or measuring value-controlled manner. Time-controlled transmission of a measured value denotes that the field device transmits the measured value either at regular intervals or always at the same time. Event-controlled transmission of a measured value denotes that data transmission takes place when a particular event occurs, for example when an error condition in the field device occurs. Measuring-value controlled transmission of a measured value denotes that, for example, the corresponding measured value is transmitted whenever a new measured value is present. This can also denote that a measured value is transmitted whenever a defined threshold value is either exceeded or not reached.
GSM-, GPRS- or UMTS modems may be used as communication modules; however, these modems require a relatively large amount of energy for the transmission of data.
For this reason such field devices are often connected to an energy supply so that at any point in time the supply of adequate energy to the field device is ensured.
It is an object of the invention to increase the flexibility in the use of field devices.
Stated are a control device for a field device for energy-controlled data transfer to an external receiver, a field device, a method for energy-controlled data transfer, a program element and a computer-readable medium according to the features of the independent claims. Further embodiments of the invention are stated in the subordinate claims.
The various exemplary embodiments equally relate to the control device, the field device, the method, the program element and the computer-readable medium. In other words, features that below are, for example, described with regard to the control unit can also be implemented in the method, the program element and the computer-readable medium and vice versa.
According to an exemplary embodiment of the invention, a control device for a field device for energy-controlled data transfer to an external receiver is stated, wherein the control device is designed to monitor a quantity of energy collected by the field device, and wherein the control device is designed to trigger the data transfer after the collected quantity of energy has exceeded a predetermined settable threshold value.
In other words, the control device can, for example, check whether the quantity of energy collected in the field device is adequate to carry out data transfer. There are various options to achieve this. For example, the control device can regularly measure the collected quantity of energy that is available in the field device, and can initiate data transfer (and prior acquisition of measured values) when the collected quantity of energy is adequate for this. Furthermore, it is possible for the collected quantity of energy to be measured only when data transfer is to take place at all. If at this point in time the quantity of energy collected is sufficient, data transfer can take place.
According to a further exemplary embodiment of the invention, data transfer is triggered as soon as adequate energy for data transfer has been collected in the field device.
A corresponding energy storage device of the field device thus charges, and, as soon as the charge state of the energy storage device is adequate, data transfer of the measured value or values takes place.
According to a further exemplary embodiment of the invention, data transfer is triggered as soon as both a first condition and a second condition are met.
The first condition may, for example, relate to the collected quantity of energy having exceeded a predetermined threshold value. If this is the case and if in addition a second condition has also been met, the measured values or some other data are transferred.
The second condition may, for example, relate to a certain pre-set period of time since a previous data transfer has elapsed. If this period of time has elapsed, the control device checks whether adequate energy is present and then triggers data transfer. The second condition may also relate to an error condition having occurred in the field device. If such a state (or some other particular defined state) has occurred, a check is made to determine whether adequate energy is available, and this is followed by data transfer. The second condition may also relate to a particular measured value having been detected (by the measuring electronics of the field device) or to a detected measured value having exceeded, or failed to reach, a particular threshold. If this is the case, data transfer takes place if sufficient energy is available for this.
Of course, the available quantity of energy may also have been measured beforehand so that the data can be transferred immediately after it is detected that the second condition has been met.
According to a further exemplary embodiment of the invention, the control device comprises a time control device that prevents data transfer from being triggered anew before a programmable, pre-settable period of time has elapsed.
According to a further exemplary embodiment of the invention, a field device comprising a control device as described above and below is stated.
According to a further exemplary embodiment of the invention, the field device comprises an energy storage device for storing the quantity of energy collected by the field device.
The energy storage device may, for example, be an accumulator or a capacitor circuit.
According to a further exemplary embodiment of the invention, the field device comprises an energy converter for collecting energy from the surroundings of the field device. It is not necessary for the field device to be connected to external energy sources.
The energy converter is, for example, one or several solar cells (solar panels) or a thermal element for so-called thermo-harvesting, in which a temperature difference is converted to electrical energy. Furthermore, the energy converter may be a wind power plant.
According to a further exemplary embodiment of the invention, the field device is designed as a fill-level measuring device, pressure measuring device, limit measuring device or flow measuring device.
According to a further exemplary embodiment of the invention, the field device is designed for installation in a tank, storage container or silo.
According to a further exemplary embodiment of the invention, the field device is designed for a providing self-sufficient energy supply by means of the energy converter or the energy converters.
According to a further exemplary embodiment of the invention, the field device further comprises a communication module for wireless communication with a central station.
According to a further exemplary embodiment of the invention, a method for the energy-controlled data transfer from a field device to an external receiver is stated, in which method the quantity of energy collected by the field device is monitored. After the quantity of energy collected has exceeded a predetermined threshold value, data transfer is triggered.
In addition to this criterion it may be provided for still other criteria having to be met for triggering data transfer. For example, this may relate to a defined period of time having elapsed since the last data transfer, to exceeding or failing to reach a defined measuring value, and/or to the occurrence of a particular state in the field device.
According to a further exemplary embodiment of the invention, a program element is stated which, when executed on a processor of a control device for a field device, instructs the processor to implement the steps described above and below.
According to a further exemplary embodiment of the invention, a computer-readable medium is stated on which a program element is stored, which, when executed on a processor in the control device for a field device, instructs the processor to implement the steps described above and below.
The program element may, for example, be part of software that is stored on a processor of the field device electronics. In this arrangement the processor may also form part of the invention. Furthermore, the term “program element” may also refer to those program elements that use the invention from the outset, or to those program elements that cause an existing program to use the invention by means of an update.
Below, exemplary embodiments of the invention are described with reference to the figures.
The illustrations in the figures are diagrammatic and not to scale. In the following description of the figures the same reference characters are used for identical or similar elements.
The first energy converter 101 is a solar panel that comprises several solar cells. The second energy converter 102 is a thermal element, in other words a device for converting a temperature difference, which is for example present between a region of the field device and the surroundings, to electrical energy. The third energy converter 103 is a wind power plant. Other energy converters, which render the field device independent of external energy supply devices may also be provided.
Various interfaces may be provided on the control device 100 in order to connect the various energy converters to them.
Furthermore, an energy storage device 112 is connected to the control device 100. The energy storage device 112 is, for example, an accumulator and/or a capacitor arrangement.
The control device 100 comprises a calculation unit 111 that carries out the described control processes. Furthermore, a time control device 110 is provided which is, for example, integrated in the control device 100 and which prevents any data transfer being triggered anew before a programmable predetermined time has elapsed.
A field device sensor may be connected to the control device 100 by way of the line 105, which field device sensor forwards the measured values to the control device 100.
Moreover, a further interface is provided to which the communication module 104 can be connected. This is, for example, a GSM-, GPRS- or UMTS modem. Other wireless transmission techniques may also be used, for example Bluetooth, WirelessHART or WiMax. The communication module 104 is used for communication without cables with an external station 107. For this purpose the wireless communication path 108 is provided.
Furthermore, the electronics 109, and in particular the communication module 104, may be designed in such a way that connection to wired communication can take place. For example, the electronics 109 (if desired) can be connected to a two-conductor loop 106.
The field device 204 is a pressure measuring device, while the field device 205 is a flow measuring device. Each of the field devices comprises electronics 109 according to the invention.
The field devices obtain their energy from the environment, for example with the use of solar cells, by means of thermal harvesting or by means of a wind power plant. The acquired measured values are transmitted to a higher-order unit 107 by way of the communication module 104.
Since the point in time at which sufficient energy for data transmission has been collected from the environment is not predictable, an additional control device is implemented in the field device. This control device monitors the quantity of energy collected from the environment, and, when the energy threshold required for transmission has been reached, triggers data transmission by way of the communication module. The control device 100 furthermore comprises a time control device that prevents excessively frequent transmission of data. This makes it possible for enough energy to be collected in the energy storage device so that, even in times in which no energy can be collected from the environment, data can still be transmitted at regular intervals.
If data transmission is to take place in a time-controlled manner, then it should be ensured that at the respective point in time enough energy is available for data transmission. If data transmission takes place in an event-controlled manner, then sufficient energy for data transmission must be available at all times, because it is not predictable at what point an error condition occurs in the field device.
If the energy is to be obtained from the environment, then, for example, a solar panel or some other energy converter must be dimensioned such that the energy requirements of the field device are taken into account.
In many applications it is sufficient if a measured value is transmitted at irregular intervals. This is the case, for example, when monitoring storage tanks 202.
For this application a comparatively small energy converter (for example in the form of a solar panel) is used, which energy converter for a particular duration collects energy from the environment. As soon as sufficient energy has been collected and stored, the control device starts the field device in order to determine the measured value at the time. Subsequently transmission of the measured value is initiated.
Such a small solar panel is not able to supply sufficient energy for permanent operation or for foreseeable operation of the field device and for data transfer. With the use of the control device according to the invention, considerably smaller energy converters can be used to supply the field device. Self-sufficient energy supply to the field device is thus possible with simple means without the energy converters needing to comprise a corresponding size.
Nor is it necessary to dimension these energy converters with regard to the energy to be supplied. For example, the control unit may be set in such a way that messages and measured values are at most transmitted three times a day.
The process steps shown may also have a different order. For example, it is possible for the charge state of the energy storage device to be controlled only, or even, when a particular event has occurred, for example if a particular period of time has elapsed or if a particular operating state in the field device has occurred.
During the individual measuring processes the control unit may be in a non-operative state (energy-saving standby mode).
In particular, it is also possible for the measuring process to be triggered from the outside. For example, a user can request a measuring process by way of a handheld device, after which the control unit checks whether enough energy has been collected for this.
In addition, it should be pointed out that “comprising” does not exclude other elements or steps, and “a” or “one” does not exclude a plural number. Furthermore, it should be pointed out that characteristics or steps which have been described with reference to one of the above exemplary embodiments can also be used in combination with other characteristics or steps of other exemplary embodiments described above. Reference characters in the claims are not to be interpreted as limitations.
| Number | Date | Country | Kind |
|---|---|---|---|
| 09 159 806.0 | May 2009 | EP | regional |
The present application is based on, and claims priority of, the U.S. Provisional Application No. 61/167,974, filed on 9 Apr. 2009, whose priority is herewith claimed, and whose disclosure is herewith included by a reference.
| Number | Date | Country | |
|---|---|---|---|
| 61167974 | Apr 2009 | US |
