DE102022133650A1 - System and method for accessing a control unit to at least one field device - Google Patents

Abstract

The invention comprises a system for accessing at least one field device (FG1, FG2, FG3) from an operating unit (BE), comprising:- the at least one field device (FG1, FG2, FG3);- the operating unit (BE), wherein a predetermined operating system with at least one framework application (RA) is provided on the operating unit (BE), wherein the framework application (RA) is a Field Device Tool (FDT) framework application, wherein a first subcomponent (TK1) of a communication driver and at least one device driver are implemented in the framework application (RA) for each field device (FG1, FG2, FG3), and wherein the at least one device driver contains operating functionalities for the corresponding field device (FG1, FG2, FG3); and- a communication server (KS), wherein a second subcomponent (TK2) of the communication driver is executed in the communication server (KS), wherein the first subcomponent (TK1) transmits a request or an operating command of the at least one device driver in a first OPC UA-compliant telegram to the communication server (KS) via an OPC UA network (KN1), and wherein the second subcomponent (TK1) of the communication driver transmits the request or the operating command received via the first OPC UA-compliant telegram in a first fieldbus protocol-compliant telegram via a fieldbus system (FS) to the field device (FG1, FG2, FG3), as well as a method for execution in the system according to the invention.

Description

The invention relates to a system for accessing at least one field device from an operating unit. Furthermore, the invention relates to a method for accessing at least one field device from an operating unit.

Field devices that are used in industrial plants are already known from the state of the art. Field devices are often used in process automation technology as well as in production automation technology. In principle, field devices are all devices that are used close to the process and that provide or process process-relevant information. Field devices are used to record and/or influence process variables. Measuring devices or sensors are used to record process variables. These are used, for example, for pressure and temperature measurement, conductivity measurement, flow measurement, pH measurement, level measurement, etc. and record the corresponding process variables pressure, temperature, conductivity, pH value, level, flow, etc. Actuators are used to influence process variables. These are, for example, pumps or valves that can influence the flow of a liquid in a pipe or the level in a container. In addition to the measuring devices and actuators mentioned above, field devices also include remote I/Os, radio adapters or general devices that are arranged at the field level.

A large number of such field devices are produced and distributed by the Endress+Hauser Group.

In modern industrial plants, field devices are usually connected to higher-level units via communication networks such as fieldbuses (Profibus ^® , Foundation ^® Fieldbus, HART ^® , etc.). The higher-level units are usually control systems (DCS) or control units such as a PLC (programmable logic controller).

The higher-level units are used, among other things, for process control, process visualization, process monitoring and for commissioning the field devices. The measured values recorded by the field devices, in particular by sensors, are transmitted via the respective bus system to one (or possibly several) higher-level units. In addition, data transmission from the higher-level unit to the field devices via the bus system is also required, in particular for the configuration and parameterization of field devices and for controlling actuators.

The integration of field devices into object-based configuration or management systems is carried out using device descriptions, which ensure that the higher-level units can recognize and interpret the data provided by the field devices. The device descriptions for each field device type or for each field device type in different applications are provided by the respective device manufacturer. In order for the field devices to be integrated into different fieldbus systems, it must also be noted that different device descriptions must be created for the different fieldbus systems. For example, there are HART, Fieldbus Foundation and Profibus device descriptions.

In order to create a uniform description for field devices, the Fieldbus Foundation (FF), the HART Communication Foundation (HCF) and the Profibus User Organization (PNO) have created a uniform electronic device description (EDD); this is defined in the IEC 61804-2 standard.

For full operation of field devices, special device descriptions, so-called DTMs - Device Type Manager or Device Manager - have recently become available, which correspond to the FDT - Field Device Tool - specifications.

The FDT specification, which is considered an industry standard, was developed by the PNO - Profibus User Organization - in cooperation with the ZVEI - Central Association of Electrical Engineering and Electrical Manufacturers. The latest FDT specification is available from the ZVEI or the PNO or the FDT Group.

Many field device manufacturers already supply the corresponding DTMs with their field devices. The DTMs include all device-specific data, functions and operating rules, such as the device structure, existing communication options and the graphical user interface, i.e. the GUI, for a specific field device or for a specific field device family.

The DTMs require a frame application as a runtime environment, here the FDT frame. The frame application and the corresponding DTMs allow very convenient access to field devices, e.g. to device parameters, measured values, diagnostic information, status information, etc., as well as calling up special functions that are available to individual DTMs. The frame application and DTMs together form a subcomponent-based management or configuration system for field devices. In order for the DTMs from different manufacturers to function correctly in the frame application, n, the interfaces to the frame application and to the other DTMs must be clearly defined. This interface definition is hidden behind the abbreviation FDT. FDT technology standardizes the communication interface between field devices and higher-level units. The special thing about this technology is that it works independently of the communication protocol used and the respective software environment of both the field device and the higher-level system. FDT makes it possible to address any field device via any higher-level system using any protocol. One well-known FDT frame is, for example, the "FieldCare" distributed by the Endress+Hauser Group.

In addition to the device drivers (DTMs), which are specifically designed for each field device type, the FDT technology provides for other driver types: gateway drivers and communication drivers. A gateway driver (gateway DTM) is a DTM that is specifically designed for a gateway device. A gateway is a network device that connects different network segments and, if necessary, ensures protocol conversion between the connected network segments. The gateway driver is integrated into the frame application like a device driver and enables the gateway to be configured and operated from the frame application.

A communication driver (CommDTM) is integrated into the frame application like the device drivers and the gateway drivers. It ensures that the operating commands or requests to a field device created by a device driver are converted into the corresponding protocol of the fieldbus network.

Examples of FDT systems that also use communication drivers (CommDTMs) are in the DE 103 13 389 A1 , in the EN 10 2005 063 162 A1 , in the EN 10 2007 058 606 A1 , in the EN 10 2009 027 949 A1 , in the EN 10 2009 045 386 A1 , in the EN 10 2011 077 787 A1 and in the US9,513,785 B2 described.

In automation systems, particularly in the subgroup of process automation, the production network (OT = "Operation Technology"), which includes the fieldbus system or the fieldbus systems with the control units, network devices and field devices, as well as the control room of the system, is separated from the infrastructure (IT = "Information Technology") and specially protected. For maintenance and commissioning, a connection is established to the field devices and data is exchanged using FDT technology. Since, as already described, FDT establishes protocol-specific communication (PROFINET, Ethernet/IP, Modbus, HART-IP) in the network, securing it involves a great deal of effort. The FDT host is therefore usually connected to the OT network. In addition, most protocols communicate in an unsecured manner and without authentication. This represents an increased risk for the system, which can only be secured to a limited extent even with VPN. If the FDT host is compromised, the entire OT network is at risk.

Based on this problem, the invention is based on the task of presenting a method which enables secure access to field devices using FDT technology from the IT level.

The object is achieved by a system according to patent claim 1 and by a method according to patent claim 1. Advantageous embodiments are described in the subclaims.

• - das zumindest eine Feldgerät, welches in einer Anlage der Automatisierungstechnik eingesetzt ist und zum Erfassen und/oder Beeinflussen von physikalischen, chemischen und/oder biologischen Größen eines verfahrenstechnischen Prozesses ausgestaltet ist, wobei das Feldgerät in ein Feldbussystem der Automatisierungstechnik eingebunden ist;
• - die Bedieneinheit, wobei auf der Bedieneinheit ein vorgegebenes Betriebssystem mit zumindest einer Rahmenapplikation vorgesehen ist, wobei die Rahmenapplikation eine Field Device Tool(FDT)-Rahmenapplikation ist, wobei in die Rahmenapplikation eine erste Teilkomponente eines Kommunikationstreibers und pro Feldgerät zumindest ein Gerätetreiber ausgeführt ist, und wobei der zumindest eine Gerätetreiber Bedienfunktionalitäten für das entsprechende Feldgerät beinhaltet; und
• - einen Kommunikationsserver, wobei das Feldgerät über das Feldbussystem in Kommunikationsverbindung mit dem Kommunikationsserver steht, wobei der Kommunikationsserver mit der Bedieneinheit über ein OPC UA-Netzwerk in Kommunikationsverbindung steht, wobei eine zweite Teilkomponente des Kommunikationstreibers in dem Kommunikationsserver ausgeführt wird, wobei die erste Teilkomponente des Kommunikationstreibers dazu ausgestaltet ist, eine Anfrage oder einen Bedienbefehl des zumindest einen Gerätetreibers in einem ersten OPC UA-konformen Telegramm an den Kommunikationsserver über das OPC UA-Netzwerk zu übermitteln, und wobei die zweite Teilkomponente des Kommunikationstreibers dazu ausgestaltet ist, die per erstem OPC UA-konformem Telegramm erhaltene Anfrage, bzw. den Bedienbefehl, in einem ersten feldbusprotokollkonformen Telegramm an das Feldgerät zu übermitteln.

With regard to the system, it is intended that it is designed for access from an operating unit to at least one field device and comprises the following components:

• - the at least one field device which is used in an automation technology system and is designed to detect and/or influence physical, chemical and/or biological variables of a process engineering process, wherein the field device is integrated into a fieldbus system of the automation technology;
• - the operating unit, wherein a predetermined operating system with at least one framework application is provided on the operating unit, wherein the framework application is a Field Device Tool (FDT) framework application, wherein a first subcomponent of a communication driver and at least one device driver per field device are implemented in the framework application, and wherein the at least one device driver contains operating functionalities for the corresponding field device; and
• - a communication server, wherein the field device is in communication connection with the communication server via the fieldbus system, wherein the communication server is in communication connection with the operating unit via an OPC UA network, wherein a second subcomponent of the communication driver is executed in the communication server, wherein the first subcomponent of the communication driver is designed to execute a request or an operating command of the at least one device driver in a first OPC UA-compliant telegram to the communication server via the OPC UA network, and wherein the second subcomponent of the communication driver is designed to transmit the request received via the first OPC UA-compliant telegram, or the operating command, to the field device in a first fieldbus protocol-compliant telegram.

According to the invention, it is therefore provided to divide the communication driver, which is usually implemented in the frame application of the control unit, into two subcomponents. Normally, the task of the communication driver is to specifically implement the FDT communication protocol and, for example, to send it over the network to which the control unit is connected. In the method according to the invention, a subcomponent of the communication driver now establishes a protocol-independent communication via OPC-UA to a second subcomponent of the communication driver. This converts the communication into a fieldbus-specific protocol.

This division allows the control unit to be separated from the OT level. The use of the OPC UA protocol makes it easy to check communication and, if necessary, to secure it, for example using certificates. Telegrams that are created in accordance with unprotected fieldbus protocols are also transported securely over the OPC UA network. A possible firewall between the control unit and the fieldbus system can also be omitted.

It may also be planned to restrict the scope of permitted communication in the communication server. If the control unit is subsequently compromised, access to the OT level of the system is restricted to the supported area of the communication server.

Examples of field devices which are mentioned in connection with the invention have already been listed in the introductory part of the description.

According to an advantageous embodiment of the system, the second subcomponent of the communication driver is designed to transmit a content of a second fieldbus protocol-compliant telegram received from the at least one field device to the control unit in a second OPC UA-compliant telegram. The system thus also enables the field device's response to be sent back to the control unit. This happens in a similar way to the outward path, with the second subcomponent of the communication driver now converting the telegram into an OPC UA-compliant telegram.

One embodiment of the system provides that the operating unit is designed to act as an OPC UA client in the communication connection with the communication server. Accordingly, the communication server is designed to act as an OPC UA server in the communication connection with the operating unit.

In one embodiment of the system, the operating unit is a computer unit, in particular a stationary PC or a laptop.

It can also be provided that other types of operating units, for example mobile devices (such as smartphones or tablets) or operating units such as the "Field Xpert" sold by the Endress+Hauser Group, can be used in the system according to the invention. The prerequisite for this is that their operating system allows the execution of an FDT frame application.

According to one design of the system, the control unit is arranged in an IT network level of the system. The IT network level describes the network level that is outside the OT network level. The OT network level includes, for example, the fieldbus system, control units, network devices and field devices, as well as the control room of the system.

An advantageous embodiment of the system provides that the second subcomponent of the communication driver implements a communication stack specific to the protocol of the fieldbus system. The communication stack manages both the communication to the field device, i.e. the creation of telegrams that conform to the fieldbus protocol, and the communication received from the field device, i.e. the processing of telegrams that conform to the fieldbus protocol. It can also be provided that several second subcomponents of the communication driver are provided on the communication server, each of which can serve different fieldbus protocols, or that the second subcomponent implements several different fieldbus-specific communication stacks, i.e. those designed for different fieldbus protocols.

• - Generieren einer an das zumindest eine Feldgerät vorgesehene Anfrage oder eines Bedienbefehls mittels dem dem Feldgerät zugeordneten Gerätetreiber;
• - Erstellen eines ersten OPC UA-konformen Telegramms durch die erste Teilkomponente des Kommunikationstreibers, wobei das erste OPC UA-konforme Telegramm die Anfrage, bzw. den Bedienbefehl enthält;
• - Übermitteln des ersten OPC UA-konformen Telegramms von der Bedieneinheit an den Kommunikationsserver über das OPC UA-Netzwerk;
• - Erstellen eines ersten feldbusprotokollkonformen Telegramms durch die zweite Teilkomponente des Kommunikationstreibers, wobei das erste feldbusprotokollkonforme Telegramm die Anfrage, bzw. den Bedienbefehl enthält; und
• - Übermitteln des ersten feldbusprotokollkonformen Telegramms von dem Kommunikationsserver an das Feldgerät über das Feldbussystem.

With regard to the method, it is intended that it serves to access at least one field device from an operating unit. The field device is used in an automation system and influences and/or records physical mechanical, chemical and/or biological variables of a process engineering process, wherein the field device is integrated into a fieldbus system of automation technology, wherein a predetermined operating system with at least one framework application is provided on the operating unit, wherein the framework application is a Field Device Tool (FDT) framework application, wherein the framework application executes a first subcomponent of a communication driver and at least one device driver per field device, wherein the at least one device driver contains operating functionalities for the corresponding field device, wherein a communication server is provided with which the field device is in communication connection via the fieldbus system and with which the operating unit is in communication connection via an OPC UA network, wherein the communication server executes a second subcomponent of the communication driver. The method according to the invention comprises the following method steps:

• - generating a request or an operating command intended for the at least one field device by means of the device driver assigned to the field device;
• - Creation of a first OPC UA-compliant telegram by the first subcomponent of the communication driver, whereby the first OPC UA-compliant telegram contains the request or the operating command;
• - Transmitting the first OPC UA compliant telegram from the control unit to the communication server via the OPC UA network;
• - Creation of a first fieldbus protocol-compliant telegram by the second subcomponent of the communication driver, wherein the first fieldbus protocol-compliant telegram contains the request or the operating command; and
• - Transmitting the first fieldbus protocol compliant telegram from the communication server to the field device via the fieldbus system.

Like the system according to the invention, the method according to the invention enables secure communication between an operating unit with an FDT system and a field device from the OT level of the system. The division of the communication driver into two subcomponents, which are divided between the operating unit and a communication server, allows the use of the secure OPC UA protocol. The protocol of the fieldbus system is thus tunneled through the OPC UA communication.

• - Generieren eines zweiten feldbusprotokollkonformen Telegramms mittels des Feldgeräts, wobei das zweite feldbusprotokollkonformen Telegramm eine Antwort des Feldgeräts enthält;
• - Übermitteln des zweiten feldbusprotokollkonformen Telegramms von dem Feldgerät an den Kommunikationsserver über das Feldbussystem;
• - Erstellen eines zweiten OPC UA-konformen Telegramms durch den Kommunikationsserver, wobei das zweite OPC UA-konforme Telegramm die Antwort des Feldgeräts enthält; und
• - Übermitteln des zweiten OPC UA-konformen Telegramms von dem Kommunikationsserver an die Bedieneinheit über das OPC UA-Netzwerk.

According to an advantageous embodiment of the method, it is provided that the method comprises the following further method steps:

• - generating a second fieldbus protocol compliant telegram by means of the field device, wherein the second fieldbus protocol compliant telegram contains a response from the field device;
• - Transmitting the second fieldbus protocol compliant telegram from the field device to the communication server via the fieldbus system;
• - Creation of a second OPC UA-compliant telegram by the communication server, wherein the second OPC UA-compliant telegram contains the response of the field device; and
• - Transmitting the second OPC UA compliant telegram from the communication server to the control unit via the OPC UA network.

This happens analogously to the outward path, whereby the second subcomponent of the communication driver now converts the telegram into an OPC UA-compliant telegram.

• 1: ein Ausführungsbeispiel des Systems.

The invention is explained in more detail with reference to the following figure. It shows

• 1 : an embodiment of the system.

In 1 a part of the communication network of a process automation system is shown. A fieldbus system FS is part of the communication network. The fieldbus system FS can have several segments. The upper segment of the fieldbus system FS is, for example, an Ethernet/IP fieldbus. Alternatively, other common protocols can also be used, such as Profibus DP or Profinet. In the example shown, a control unit PLC is connected to the upper segment of the fieldbus system FS. For example, this is a programmable logic controller (e.g. Siemens S7 Simatic).

Several field devices FG1, FG2, FG3 are connected to the PLC control unit via lower segments of the fieldbus system FS. The lower segments of the fieldbus system FS use HART as a protocol, for example. Alternatively, other fieldbus protocols can also be used, such as Foundation Fieldbus or Profibus PA.

The field devices FG1, FG2, FG3 are, for example, measuring devices which are designed with at least one sensor element for detecting a physical, chemical and/or biological variable of a process engineering process (for example temperature, pressure, fill level, flow, pH value, conductivity, etc.), or actuators which have an actuator unit for Influence such quantities (for example a pump or a valve).

The upper segment of the fieldbus system FS is connected to a third communication network KN3 via a first gateway GW1. This communication network KN3 connects components of the system's control center and is, for example, Ethernet-based. The first gateway GW1 ensures protocol implementation of telegrams exchanged between the fieldbus system FS and the third communication network KN3. A workstation PC is shown here as a component of the control center, which has, for example, DCS (= "Distributed Control System") software, by means of which values from the field devices FG1, FG2, FG3 can be received and processed, but also commands can be transmitted to the field devices FG1, FG2, FG3.

The communication networks or fieldbus systems mentioned so far and the components they contain belong to the OT network level of the system. This network level is characterized by the fact that the components it contains are subject to a strict set of rules and, in particular, there is no access from outside.

The upper segment of the fieldbus system FS is connected to a second communication network KN2 via a second gateway GW2. This communication network KN2, which is Ethernet-based, for example, is located in the IT network level IT of the system. The IT network level is an administration level that is connected to the Internet, for example. The second gateway GW1 ensures protocol implementation of telegrams that are directed from the fieldbus system FS to the second communication network KN2, or collects and filters telegrams from the fieldbus system FS that are relevant for the second communication network KN2. It can be provided that the second gateway GW2 works as a data diode and does not forward any telegrams from the second communication network KN2 to the fieldbus system FS.

An operating unit BE is arranged in the second communication network KN2. In the present embodiment, this operating unit BE is a computer unit, in particular a PC. A framework application RA, specifically an FDT framework application, runs on the operating unit BE. Device drivers for the field devices FG1, FG2, FG3 are integrated into the framework application RA, with the help of which the field devices FG1, FG2, FG3 can be operated via the operating unit BE. The term "operate" is to be interpreted broadly here and includes, for example, the writing and reading of parameter values.

To ensure secure access to the field devices FG1, FG2, FG3, the control unit BE is connected to a communication server KS via a first communication network KN1. Securing access is essential because the control unit BE is located in the IT network level IT of the system and the devices to be operated are located in the OT network level OT of the system. Data should therefore be brought from the IT network level IT into the OT network level.

The communication server KS is located in the OT network level OT of the system and is connected to the upper segment of the fieldbus system FS. The control unit BE communicates with the communication server KS via a secure first communication network KN1. The security of the first communication network KN1 is achieved by using the OC UA protocol. Telegrams can be provided with certification, for example, so that the recipient of a telegram can always verify the sender of the telegram.

The communication driver, which is usually in the frame application RA of the control unit BE for the fieldbus protocol-specific creation of a telegram, which for example contains an operating command created by one of the device drivers, or which unpacks telegrams received from the field devices FG1, FG2, FG3 in a fieldbus protocol-specific format and forwards them to the corresponding device driver, is divided according to the invention into two subcomponents TK1, TK2. The first subcomponent TK1 of the communication driver is integrated in the frame application RA of the control unit BE, whereas the second subcomponent TK2 of the communication driver is integrated in the communication server KS (also in an FDT frame application executed on the communication server KS). This system enables secure access to field devices FG1, FG2, FG3 and their operation from a control unit BE arranged in the IT network level of the system.

• Zuerst wird durch einen Bediener ein Bedienbefehl in der Rahmenapplikation gesetzt. Im vorliegenden Fall möchte der Bediener einen Diagnosewert aus dem Feldgerät FG1 auslesen. Der Gerätetreiber GT des Feldgeräts FG1 weist eine entsprechende Befehlsschaltfläche aus. Nach Betätigen der Befehlsschaltfläche erstellt der Gerätetreiber einen entsprechenden Bedienbefehl und leitet diesen an die erste Teilkomponente TK1 des Kommunikationstreibers weiter. Diese erste Teilkomponente TK1 verpackt den Bedienbefehl in ein OPC UA-konformes Telegramm. Anschließend wird dieses Telegramm von der Bedieneinheit BE über das erste Kommunikationsnetzwerk KN1 an den Kommunikationsserver KS übermittelt.

The following describes in detail how the field device FG1 is operated using the control unit BE:

• First, an operator sets an operating command in the frame application. In this case, the operator wants to read a diagnostic value from the field device FG1. The device driver GT of the field device FG1 has a corresponding command button. After pressing the command button, the Device driver receives a corresponding operating command and forwards it to the first subcomponent TK1 of the communication driver. This first subcomponent TK1 packages the operating command in an OPC UA-compliant telegram. This telegram is then transmitted from the operating unit BE to the communication server KS via the first communication network KN1.

After the telegram has been received by the communication server KS, the second subcomponent TK2 of the communication driver processes the telegram and converts it into a telegram that conforms to the fieldbus protocol. For example, OPC UA-specific preambles are removed and fieldbus protocol-specific preambles are added.

Once the fieldbus protocol-specific telegram is available, it is transmitted from the communication server KS to the field device FG1 via the segments of the fieldbus system FS.

After the field device FG1 receives the telegram, it implements the operating command and creates a response telegram in the fieldbus protocol-specific format, which contains the diagnostic value. This response telegram is transmitted to the communication server KS via the segments of the fieldbus system FS.

After the response telegram has been received by the communication server KS, the second subcomponent TK2 of the communication driver processes the telegram and converts it into an OPC UA-specific telegram. For example, fieldbus protocol-specific preambles are removed and OPC UA-specific preambles are added. This telegram is then transmitted from the communication server KS to the control unit BE via the first communication network KN1.

After receiving the response telegram, the first subcomponent TK1 unpacks the diagnostic value and forwards it to the device driver of the field device FG1. This has a display area via which the control unit presents the diagnostic value to the operator.

The system according to the invention and the associated method are not limited to the 1 The invention also covers alternative embodiments. For example, the operating unit BE can also be designed in a different form, for example as a mobile device, in particular a tablet or a smartphone.

List of reference symbols

BE

Control unit

FG1, FG2, FG3

Field devices

FS

Fieldbus system

GW1, GW2

Gateway

KN1

first communication network, OPC UA network

KN2

second communication network, IT network

KN3

third communication network, IT network

KO1

first subcomponent of the communication driver

KO2

second subcomponent of the communication driver

KS

Communication server

PC

Control center PC

R.A.

Frame application

PLC

Control unit

TK1

first subcomponent of the communication driver

TK2

second subcomponent of the communication driver

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• DE 10313389 A1 [0014]
• DE 102005063162 A1 [0014]
• DE 102007058606 A1 [0014]
• DE 102009027949 A1 [0014]
• DE 102009045386 A1 [0014]
• DE 102011077787 A1 [0014]
• US 9513785 B2 [0014]

Claims (9)

System for accessing at least one field device (FG1, FG2, FG3) from an operating unit (BE), comprising: - the at least one field device (FG1, FG2, FG3) which is used in an automation system and is designed to detect and/or influence physical, chemical and/or biological variables of a process engineering process, wherein the field device (FG1, FG2, FG3) is integrated into a fieldbus system (FS) of the automation technology; - the operating unit (BE), wherein a predetermined operating system with at least one framework application (RA) is provided on the operating unit (BE), wherein the framework application (RA) is a Field Device Tool (FDT) framework application, wherein a first subcomponent (TK1) of a communication driver and at least one device driver per field device (FG1, FG2, FG3) are implemented in the framework application (RA), and wherein the at least one device driver contains operating functionalities for the corresponding field device (FG1, FG2, FG3); and - a communication server (KS), wherein the field device (FG1, FG2, FG3) is in communication connection with the communication server (KS) via the fieldbus system (FS), wherein the communication server (KS) is in communication connection with the operating unit (BE) via an OPC UA network (KN1), wherein a second subcomponent (TK2) of the communication driver is executed in the communication server (KS), wherein the first subcomponent (TK1) of the communication driver is designed to transmit a request or an operating command of the at least one device driver in a first OPC UA-compliant telegram to the communication server (KS) via the OPC UA network (KN1), and wherein the second subcomponent (TK1) of the communication driver is designed to transmit the request or the operating command received via the first OPC UA-compliant telegram in a first fieldbus protocol-compliant telegram via the fieldbus system (FS) to the field device (FG1, FG2, FG3). System according to Claim 1 , wherein the second subcomponent (TK2) of the communication driver is designed to transmit a content of a second fieldbus protocol-compliant telegram received from the at least one field device (FG1, FG2, FG3) in a second OPC UA-compliant telegram to the operating unit (BE). System according to one of the preceding claims, wherein the operating unit (BE) is designed to act as an OPC UA client in the communication connection with the communication server (KS). System according to one of the preceding claims, wherein the operating unit (BE) is a computer unit, in particular a stationary PC or a laptop. System according to one or more of the preceding claims, wherein the operating unit (BE) is arranged in an IT network level of the system System according to one of the preceding claims, wherein the communication server (KS) is designed to act as an OPC UA server in the communication connection with the operating unit (BE). System according to one of the preceding claims, wherein the first subcomponent (TK1) of the communication driver implements a state machine of the frame application (RA). Method for accessing at least one field device (FG1, FG2, FG3) from an operating unit (BE), wherein the field device (FG1, FG2, FG3) is used in an automation system and records and/or influences physical, chemical and/or biological variables of a process, wherein the field device (FG1, FG2, FG3) is integrated into a fieldbus system (FS) of the automation technology, wherein a predetermined operating system with at least one framework application (RA) is provided on the operating unit (BE), wherein the framework application (RA) is a Field Device Tool (FDT) framework application, wherein the framework application (RA) executes a first subcomponent (TK1) of a communication driver and at least one device driver per field device (FG1, FG2, FG3), wherein the at least one device driver contains operating functionalities for the corresponding field device (FG1, FG2, FG3), wherein a communication server (KS) is provided with which the field device (FG1, FG2, FG3) via the fieldbus system (FS) and with which the operating unit (BE) is in communication connection via an OPC UA network (KN1), wherein the communication server (KS) executes a second subcomponent (TK2) of the communication driver, comprising: - generating a request or an operating command intended for the at least one field device (FG1, FG2, FG3) by means of the device driver assigned to the field device (FG1, FG2, FG3); - creating a first OPC UA-compliant telegram by the first subcomponent (TK1) of the communication driver, wherein the first OPC UA-compliant telegram contains the request or the operating command; - Transmitting the first OPC UA-compliant telegram from the operating unit (BE) to the communication server (KS) via the OPC UA network (KN1); - Creating a first fieldbus protocol-compliant telegram by the second subcomponent (TK2) of the communication driver, whereby the first fieldbus protocol-compliant telegram contains the request or the operating command; and - Transmitting the first fieldbus protocol-compliant telegram from the communication server (KS) to the field device (FG1, FG2, FG3) via the fieldbus system (FS). Procedure according to Claim 8 , further comprising: - generating a second fieldbus protocol-compliant telegram by means of the field device (FG1, FG2, FG3), wherein the second fieldbus protocol-compliant telegram contains a response from the field device (FG1, FG2, FG3); - transmitting the second fieldbus protocol-compliant telegram from the field device (FG1, FG2, FG3) to the communication server (KS) via the fieldbus system (FS); - creating a second OPC UA-compliant telegram by the second subcomponent (TK2) of the communication driver, wherein the second OPC UA-compliant telegram contains the response from the field device (FG1, FG2, FG3); and - transmitting the second OPC UA-compliant telegram from the communication server (KS) to the operating unit (BE) via the OPC UA network (KN 1).

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