Description

Automation network, automation device and electronic component, particularly a field device, for an automation network, and method for the transmission of operating data of an automation device between an automation system and a remote computer.

^• The method relates to an automation network with at least one automation device as a first electronic component of an automation system, with a second electronic component of the automation system, particularly a field device, and with at least one remote computer in accordance with the preamble of claim 1, an automation device and an electronic component, particularly a field device, for such an automation network in accordance with the preamble of claim 9 or 10 and a method for the transmission of operating data of an automation device between an automation system and a remote computer in accordance with the preamble of claim 11.

The term automation device as a first electronic device of an automation system means a device that processes a control program for controlling a process. Such devices are known as PLC (programmable logic controllers) or a soft PLC. An automation device can be of modular construction and can contain a central programmable unit and intelligent modules, that perform individual automation functions, .such as weighing, axis control, closed-loop control etc. An additional module, known as a communication processor, can be provided for connection to a communication network that serves for data exchange with other components of an automation network, for example network components or field devices or other automation devices.

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A field device means a device that can be arranged decentrally in the field, i.e. close to the controlled process in an automation network, and that exercises functions, for the detection of process variables and/or the influencing of the process. Such devices are usually known as measuring transducers, sensors, final controlling elements, actuators or I/O devices. They normally include elements for connecting to a network and use communication mechanisms usually used for automation purposes. For example, PROFINET, Ethernet IP or Modbus-TCP are examples of such Ethernet-based communication mechanisms. ^■ A communication mechanism is usually defined by the associated protocol, normally standardized, and the communication relationship on which it is based. Communication relationships organize communication between the devices participating in data transmission in the network, also known as users. Examples of communication relationships are client/server, master/slave, master/master, producer/consumer or publisher/subscriber. TCP/IP is frequently used as the communication protocol for Ethernet- based networks.

From US 6,151,625 A, a programmable logic controller is known that has a web interface for communication via the Internet or the intranet. This created a client/server system that offers users a similar user-friendly user interface, such as general access services in the Web. The Web is a network of documents, also known as pages, that are stored distributed on server computers throughout the world. Normally, a page contains text, various multimedia offers, such as graphic pictures, video or audio data, . and also hypertext links to other documents. A browser enables the user to read the pages and interactively select from the possibilities offered on

the page. The browser is a graphics program that sends requests via the Internet to a page and displays variable information on a called-up page. The web interface integrated into the programmable logic controller enables a user to call up the operating data of-the programmable logic controller by- means of a browser. The operating data can be data for control configuration, process data such as input or output values, register states, statistical data, diagnostic data or configuration data of the input-output interfaces. To operate and monitor the automation system by means of a human-machine • interface (HMI) a remote computer with an Internet connection, to a browser, for example the Navigator of Netscape Communication or Internet Explorer from Microsoft, is sufficient.

. To achieve a high availability of the automation device, and thus a high degree of reliability of the complete control operation, it is necessary to make sure that the same degree of availability is achieved for the communication with a remote computer as for the actual automation functions, so that automation functions are not disturbed by communication functions. On the other hand, -with a pure communication task a substantially lower reliability would be sufficient if it were uncritical for the automation functions. Communication functions also have a tendency to grow with time, because the complexity of the data display steadily increases. It is

• • therefore increasingly more difficult to achieve communication functions .with the same reliability as is required for the automation functions.

The object of the invention is to provide an automation network, an automation device and an electronic component, particularly a field device, for such an automation network,

and a method for the transmission of operating data of an automation network between an automation system and a remote computer, characterized by an improved reliability of the complete control operation.

To solve this problem, the automation network of the kind named in the introduction is provided with the features given in the characterizing part of claim 1. A corresponding automation device, an electronic component, particularly a field device, for an automation network and a method for transmission of operating data of an automation device between an automation system and a remote computer are described in claims 9, 10 and 11. Advantageous developments of the invention are specified in the dependent claims. ^{• ■ • '}

In an advantageous manner, the communication functions necessary for the transmission of operating data of the automation device to a remote computer are taken away from the automation device and integrated into a second electronic component of the automation system in which the automation device is located. A negative effect of communication functions on the reliability of the controlled operation of the automation device is thus prevented. Data requests made by a remote computer for the operating data of an automation device with the aid of an Internet browser are thus no longer answered by a server application running on the automation device, but instead by the second electronic component of the automation system. For this purpose, the second electronic component is provided with a server expansion in which a map of the operating data of the automation device is stored. The map is appropriately updated if the operating data changes. The communication interface required for data transmission to the remote computer is in a device which is already in the

automation system and therefore an additional device is advantageously not required. Because the communication hardware is separate from the automation device, this can be serviced independent of ^' the automation device. Furthermore, the communication capability of the second electronic component can be easily scaled, if an increasing number of automation devices are being served or monitored in ^" an automation system by one or more remote computers. Furthermore, a distribution and optimization of the communication load to the various components of an automation system is enabled.

A further advantage is an increase in the system security, because direct access to operational components of the automation device, for example to the arithmetic unit or data memory for applications that communicate with the remote computer is avoided. The danger of sabotage or unauthorized access to an automation device is therefore substantially reduced.

In principle, a server expansion to store a map of operating data of the automation device can be provided in any second electronic component of the automation system, for example in a teleservice adapter, a human-machine interface device or an operating power supply or similar. Arranging the server expansion in a field device of the automation system, however,- has the advantage that this forms a fixed component and is present not just from time to time in the automation

^■ network. An extensive availability- of the operating data of the automation device for the remote computer is thus guaranteed.

To minimize the computing power . of the automation device required for communication tasks, the amount of data transmitted by the automation device is kept to a minimum. To achieve this, the operating data map is updated when a change in the operating data of the automation device occurs . Data that has not changed since the last transmission is then not re-transmitted. The time intervals between the synchronization processes for updating the operating data map can be advantageously matched to the time intervals between access requests by the remote computer. This results in a further reduction in the amount of communication associated with updating the operating • data map. The average time intervals between the synchronization processes can therefore be configured to be both constantly and dynamically adaptable, in order to be able to follow changes in the frequency of access operations by the remote computer.

In an advantageous manner, the means for controlling access can be arranged in such a way that in the event of an access request by the remote computer for operating data of the automation device for which no map is stored in the server expansion, this operating data is transmitted from the automation ^' device via the communication network for the transmission of data with a communication mechanism of the automation field communication to the second electronic component and from this via the Internet or intranet to the remote computer. This ensures that even if the requested operating data is not stored in the operating data map no direct external access to the automation device takes place. This further increases security against unauthorized, access or sabotage.

Web pages for the display of operating data of the automation device with the Internet browser of the remote computer can initially be stored on the automation device and transmitted to the second electronic component when the automation network is commissioned. The advantage of this is that the information in the server expansion, that depends on the particular automation device, is delivered by the automation

^• device itself. It is therefore unnecessary to store several variants of web pages for various automation devices in the , server expansion of the second electronic component.

In an advantageous manner, the overall expenditure associated with an automation network is reduced if the server expansion is configured for .the storage of a map of operating data of several automation devices.

In addition, the cost of the server expansion itself can be reduced if the automation device is provided with a web client and communication for synchronization between the operating data of the automation device and its map can be performed by means of a client/server relationship. A standard communication mechanism can- thus be used both for synchronization and for answering access requests by the remote computer.

The cost of an automation network can be further reduced if in each case, as a communication mechanism of the automation field communication, a communication mechanism based on Ethernet with TCP/IP, and for communication for synchronization between the operating data of the automation device and its map, the same TCP/IP stack can be used as is provided in the automation device or in the second electronic component for automation field communication.

The invention and ^■ its embodiments and advantages are explained in ^' more detail in the following with the aid of ^■ drawings, showing examples of embodiments of the invention.

The drawings are as- follows.

Fig 1 An automation network with PROFINET for field communication ^•

Fig 2 An automation network with PROFIBUS for ' field communication

An automation network, as shown in Fig 1, • includes two automation devices 1 and 2, three field devices 3, 4 and 5, a communication network 6 for the transmission of data with a communication mechanism of the automation field communication, in this case in accordance with the PROFINET standard, a switch 7 for connecting communication network 6 to the Internet 8 or to an intranet and also a remote computer 9. The automation devices 1 and 2 and the field devices 3, 4 and 5 are interconnected within an automation system through the communication network 6 for data transmission. The switch 7, present as an option, is used to connect the communication network 6 with the Internet 8, so that data exchange is possible between the remote computer 9 and the automation system. To perform the communication, a TCP/IP stack, 11, 12, 13, 14 or 15 respectively is present in the automation devices 1 and 2 and in the field devices 3, 4 and 5. Web pages 16 and 17 are stored in automation devices 1 and 2 respectively. These web pages 16 and 17 are provided for the display of operating data of the automation devices 1 and 2 by means of an Internet browser 19 of the remote

computer 9 and are loaded to- a web ^■ page memory 23 of the field device 3 during the start up of the automation system. Furthermore, operating data 26 .and ^' 27 of the automation devices 1 and 2 are each transmitted in an assigned operating data map 28 or 29. The field device 3 is provided with a web server application 32 in a server expansion 31 in which the operating data maps 28 and 29 and the web pages 23 are stored. Both TCP/IP stacks 11 and 12 of the automation devices 1 and 2 each have the additional function of a synchronization unit that updates the operating data map 28 or 29 when the operating data 26 or 27 changes. Automation devices 1 and 2 have a client application in their particular

TCP/IP stack 11 or 12, so that the transmission of the

Operating data and the web pages can take place by means of a client/server relationship. The web server application 32 in the server expansion 31 of the field device 3 also uses the TCP/IP stack 13 for communication with the remote computer 9, with the operating data 28 or 29 of the automation devices 1 and ^• 2 being transmitted ^" via ;. the Internet . 8 using the Hypertext- Transfer Protocol and displayed and changed on the remote computer 9 using the Internet browser 19. To keep the communication load on the communication network 6, that occurs due to the synchronization between . the operating data 26, 27 and its map 28 or 29, within limits, the updating takes place at time intervals matched to the frequency of the access requests of the remote computer 9. In the event of an access request from the remote computer 9 for operating data 26 or 27 of the automation devices 1 or 2, this is diverted by means of an access control, contained in the data transmission interfaces of the automation devices 1 and 2 and the field device 3, to the relevant operation data map 28 or 29 in the server expansion 31, thus enabling the relevant data of the ■ operating data map to be transmitted via the

• Internet 8 to the remote computer 9. The web server application 32 fills the requested web page, stored in the web page memory 23, with ^' the requested operating data from the server expansion 31 and. transmits the completed web page to the Internet browser 19.

There are various means whereby access requests from the

• remote computer 9 can be diverted to an operating data map 28 or 29 in the server expansion 31. For example, the server expansion 31 can operate as a proxy and answer access request directed to one of the automation devices 1. or 2 itself instead of the automation device. Another possibility is that the automation devices 1 and 2 contain a minimalistic web server that simply answers access requests from, the remote computer 9 in that these are diverted to the server expansion 31 in the field device 3. A further possibility is that a further HTTP proxy is expanded so that the access requests directed to an automation device are diverted to the relevant operating data map in the server expansion by corresponding re-addressing.

An alternative to the example of an embodiment shown, in which the server expansion 31 is, integrated into the field device 3, it is of course possible to provide several server expansions that, for example, are each assigned to an automation device in various field devices . As a further alternative it is possible to arrange a corresponding server expansion in a different electronic component ■ of the automation system, for example, in a power supply unit, in a human-machine interface or in a teleservice adaptor that has suitable hardware and a connection to the communication network 6.

In the event of an access request from the remote computer 9, for example for operating data 26 of the automation device 1 for which no operating data map is stored ^' in the server expansion 31, this operating data 26 is first transmitted from the automation device 1 via the communication network 6 to the field device 3 and then from there via the Internet 8 to the remote computer 9. This makes sure that no direct access to the automation device 1 takes place in this case either.

The described arrangement of the server expansion in the field device 3 has the advantage that the communication hardware can be serviced independently of the hardware of the automation devices 1 and 2. If the computer performance of the field device is sufficient for the additional communication tasks, no additional hardware expansions are necessary to cater for the server expansion.

Fig 2 shows an alternative form of embodiment of an automation network whereby a communication, network 40 . is designed according to the PROFIBUS standard.- Automation devices 41 and 42 and field devices 43, 44 and 45 with their interfaces 46, 47, 48 and 49 and 50 are connected to the PROFIBUS communication network 40. Similar, to the automation network explained ^' with the aid of Fig 1, a server expansion 51 of the field device 43 contains an operating data map 52 for the operating data 53 of the automation device 41 and an operating data map 54 for operating data 55 of the automation device 42. The server expansion 51 of field device 43 also contains a memory 56 for web pages of the automation devices 41 and 42 and also a server application 57. A remote computer 60 with a web browser 61 is connected to the Internet 62. To enable the automation system to be accessed via the Internet,

the field device 45 has a protocol converter expansion 63 with a TCP/IP stack 64 that forms an interface to the Internet 62. Access requests- by the web browser 61 are passed via the Internet 62 to the protocol converter expansion 63, that ensures that access requests for operating data 53 or 55 of the automation device 41 or 42 are diverted to their operating data map 52 or 54. This, in turn, . makes sure that direct access via the Internet 62 to one of the automation devices 41 or 42 is not possible. The synchronization and access control between the operating data and operating data map can take place as shown in Fig 1. As an alternative to the use of a protocol converter expansion 63, a protocol converter 70 can be provided between the PROFIBUS communication network 40 and the Internet 62, as shown by a broken line in Fig 2. As ah interface to the Internet 62, the protocol converter 70 has a TCP/IP stack 71, and a PROFIBUS connection 72 as the interface to the PROFIBUS communication network 40. In this case, the access control can take place by a suitable configuration of the PROFIBUS connection 72 in such a way ^' that access requests for operating data of the automation devices 41 and 42 are always diverted, to the map 52 or 54 in the server expansion 51 of the field device 43..