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1. CA2422920 - METHOD OF MAKING MEASURED VALUES AVAILABLE TO FINAL CUSTOMERS

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]
19-MAR-2003 16:31 E+H PATSERUE WELL +49 7621 975
Method of Making Measured Values Available to
Final Customers
This invention relates to a method of making measured values available to final customers.
In process automation, field devices are in common use which control processes in manufacturing plants.
Examples of field devices are level gauges which determine the level of a liquid in a tank, pressure gauges Which determine the pressure of a liquid or gas, e.g. in a pipe, mass flowmeters which determine the mass flow rate of a liquid in a section of pipe, or valves which control the flow rate in a section of pipe.
Field devices can be divided essentially into two groups, namely sensors, which determine a process variable such as level, pressure, mass flow rate, or temperature, and actuators, which act an a process variable such as the flow rate in a pipe section. An example of actuators are valves.
As a rule, field devices are connected via a data link to a process control system which controls the entire sequence of operations in a manufacturing plant.
18-MItiR-2003 16:31 E+H PATSERUE WELL 4-49 7621
SRS 888 S.03,12
Data transmission on such a data link is governed by the known standards, such as Hart, Profibus, or Fieldbus.
Over the data link, the measured values provided by a sensor are transmitted to the process control system, where they are processed. The control instructions from the process control system are transmitted over the data link to the appropriate actuators, which then respond accordingly, for instance by opening or closing a valve.
The field devices are sold to the final customer, who uses them at the desired process component.
In some cases, the process components are not spatially concentrated at a manufacturing plant, but are distributed, so that a direct connection from the field devices to a process control system, e.g. via a data bus system, would be too costly. Examples of such process components are distributed fuel tanks and lime containers for combating damage done to forests by acid rain, which are set up in forest areas at widely scattered locations.
In that case, the data transmission to the process control system is by radio.
To the final customer, strictly speaking, only the measured value provided by the sensor is of interest. only this value is needed in the customer's process control system to control the manufacturing plant.
How the measured value is obtained is unimportant to the final customer. What is important to the final customer ak 02422920 2013-11-25 is that a reliable measured value is made available to him or her.
Nowadays the final customer pays for the sensor and not for what he or she actually needs, the measured value.
A defective sensor does not provide measured values and
Is thus of no use to the final customer. The final customer does not want to pay for a sensor that does not provide measured values.
Some final customers need the measured values at relatively short time intervals, while others need the measured value relatively seldom. However, both final customers pay the same amount of money for the sensor even though they use it differently frequently.
Some embodiments of the invention may provide a method of making measured values available to final customers which does not have the above-mentioned disadvantages and particularly permits measured values to be made available to final customers at low cost.
According to some embodiments of the invention, there is provided a method comprising the following steps: 1. Measuring a value of a process variable by means of a sensor. 2. Transmitting the measured value to a process control system.
ak 02422920 2014-12-11 3. Counting the number of transmission. operations. 4. calculating the costs to be charged to the final = customer .on the basis of the number of transmission operations. .
Some embodiments of the invention may provide that the final customer pays no longer for the sensor itself, but only for what the customer actually needs, namely the measured value.
The data transmission between sensor and process control system..may be via a line link, e.g. via a data bus system, or by radio.
The number of transmission operation s may be stored in the sensor or in the process contrOl system.
/n a further development of the invention, the measured values are sent over the Internet to the field-device manufacturer and stored there in a database. The final customer accesses this database also via the Internet when the measured value is needed. In this development, the number of databases acceopeo is counted.
In an alternative development of the invention, the measured values are sent by radio, e.g. via GSM, to a provider that is. linked to. the field-device manufacturer.
In that case, too, the measured values are stored in 'a .
database at the field-device manufacturer and can be made available to the final customer on request.
According to one embodiment of the invention, there is provided a method for providing measured values for end customers, 5 comprising the steps of: recording a process variable by a measured value pick-up device wherein the device, a converter, a computer unit and a communication unit are part of a sensor; digitizing the process variable into a measured value by the converter connected to the device via a first data line; transmitting the measured value from the converter to the computer unit; transmitting the measured value from the computer unit to the communication unit over a second data link; receiving by the sensor a request for the measured unit from a process control unit; converting the measured value by the communication unit into a message and transmitting the message from the sensor to the process control unit wherein the message comprises the measured value, data bus address of the sensor S and a data bus address of the process control system; and counting and storing the number of measured values transmitted from the sensor to the process control unit by the computer unit.
The invention will become more apparent from the following description of a preferred embodiment when taken in conjunction with the accompanying drawing, in which:
Fig.1 is a schematic representation of a data bus system with several sensors which are connected to a process control system by a data bus;
Fig. 2 is a block diagram of a sensor.
The data bus system DBS shown in Fig. 1 comprises several devices, namely a process control system PLS, several sensors
S, several actuators A, and a measured value display unit MA, which are interconnected via a data bus DBL. The process control system PLS is, as a rule, located in a control room, from which the process control is effected. The sensors S and actuators A are located "in the field" at the individual process components (tank, filling equipment, pipeline, etc.) and are therefore referred to as "field devices". The process variable sensed by the sensors Si, S2, and S3 are, for instance, the temperature T, the pressure D, and the flow rate
F at a given process component. The actuators Al and A2 are, for example, valve operating mechanisms which control the flow rate of a liquid or gas in a pipe.
Data communication between the process control system PLS, the sensors S, and the actuators A is carried out in the known manner according to an international 1944*-2003 16:32 E+H PATSERUE WELL +49 7621 975 899 6.07/12 transmission standard (e.g., RS 485 or IEC 1188) using specific protocols (e.g., Profibus or Foundation
Fieldbus).
The data communication will now be explained in more detail with reference to the sensor Si (Fig. 2). The sensor Si senses a process variable, e.g. the temperature
T of a liquid (not shown), with a sensing element MWA and digitizes the measurement signal with an AID converter
A/D to form a measured value. The sensing element MWA and the A/D converter A/D are interconnected by a data line
DIAS'. The measured value is transferred from the A/D converter A/D over a data line DL1 to a computing unit
RE and stored there.
The computing unit RE transfers the measured value, cyclically or in response to a request from the process control system PLS, over a data line DL31 to a communications unit ICE, which converts it into a message that is placed on the data bus DBL via a data line DL21 and a Fieldbus interface FESS.
The Fieldbus interface FSS2 supports all transmitting and receiving functions according to the transmission technology used.
Aside from the digitized measured value, the message includes information about the sender and receiver in the form of data bus addresses DA, which uniquely identify each of the devices attached to the data bus. In this case, the message includes the data bus address of the temperature sensor Si and the data bus address of the desired receiver.
75089-/3 CA 02422920 2014-12-11
If the measured Value is to be transmitted from the sensor 1 to the process control system PLO, the receiver address will be the data bus address of the process control system PLS. If the process control system PLS sends a message to the temperature sensor Si, the data bus address of the temperature sensor Si will be the receiver address, and the data bus address of the process control system PLS will be the sender address.
The data bus system DDS may operate, tor example, on the master-slave principle, i.e., the process control system
PLS requests a given sensor, e.g. the sensor Si, via a corresponding message to put its measured value on the data bus DBL.
The senor 81 responds with a response message containing the measured value.
Such requests are generally made cyclically at given time intervals.
In a data bus system working on another principle, the sensors S place their measured values on the data bus DL on their own at certain time intervals (cyclically).
In the computing unit RE, the number AZ of transmissions of measured values is counted and stored in a data memory incorporated in the computing unit.
Alternatively, the number AS of measured-value transmissions may be counted in the process control system PLS and stored there in a data memory. In any case, however, any deliberate manipulation of the number
AZ of measured-value transmissions must be precluded.
A method according to an embodiment of the invention will now be explained in more detail.
19-MAR-2003 16:33 E+H PATGERUE WELL +48 7621 975 899 G.09/12
In a first step, the measured value of a process variable, e.g. temperature, pressure, or flow rate, is sensed by means of a sensor IS, e.g. Si, $2, or $3.
In a second step, the measured value is transmitted to the process control system PLS. The transmission may be effected either in response to a request from the process control system PLS or cyclically by the sensor S.
In a third step, the number AI of transmission operations is counted. In a fourth step, the costs to be charged to the final customer are calculated on the basis of the number AZ of transmission operations.
With this method it is possible in a simple manner to charge for the use of the sensor B. The final customer pays no longer for the sensor S, but for the number Az of measured values received from sensor O. The field-device manufacturer makes measured values available to the final customer at low cost.
The method according to the invention is not limited to wireline data bus systems, but can also be used with radio transmission. In that case, the sensor is linked, and the measured values are sent, to the process control system by radio.
Radio transmission is advantageous with widely scattered process components, from which a line link to the process control system does not pay.
Examples of such process components are fuel tanks or lime containers as are used to combat damage caused to forests by acid rain.
1G¨MhR-2003 16:33 E+H PATGERUE WELL +49 7621 975 eee s.ica/i2
If a radio link is used, the number AZ of measured values transmitted by radio to the process control system is counted.
More recently measured values have also been transmitted from sensors to process control systems at final customers via the Internet. In that case, manipulationproof counting of transmission operations is possible in a simple manner. The measured values are sent from the sensor to the final customer's process control system not directly, but via the field-device manufacturer. For this purpose, the field-device manufacturer makes available a database which can be accessed by the final customer. The sensor transmits the measured value via the Internet to the field-device manufacturer, where it is stored in the database. When the final customer needs the measured value, he or she will retrieve it from the database via the Internet.
In an alternative development of the invention, the measured values are sent to the field-device manufacturer by radio, e.g. via GSM. In that case, too, the measured values are stored in a database at the field-device manufacturer and can be made available to the final customer on request, e.g. via the Internet.