DE102019102617A1 - Method for accessing data and services of a network node in a network of automation technology - Google Patents

Abstract

In a method for accessing data and services of a network node in a network of automation technology, each network node presents its data and services in a hierarchical directory structure and each network node can expand its own directory structure through the directory structure of its downstream communication partner. This enables easy access to data and services across multiple network nodes are possible, in particular not only from a higher level to network nodes at a lower level, but also in the opposite direction.

Description

The invention relates to a method for accessing data and services of a network node in a network of automation technology. In particular in connection with Industry 4.0, the simple exchange of information, in particular between machines in automation networks, is becoming increasingly important.

Automation networks are typically hierarchical. The sensors and actuators are on the lowest level, with e.g. B. ASi, IO-Link as communication standards. Above that is the control level with controls (PLC, PLC industrial PC) with e.g. B. Profibus as a communication standard.

The SCADA systems are provided in the next higher level, the process control level. Ethernet connections are used for communication. The top level contains the ERP systems such as B. SAP.

The OPC Unified Architecture (OPC UA) standard offers an opportunity for information exchange, especially in the Ethernet-based levels. OPC UA is a TCP / IP based communication technology developed by the OPC Foundation. It enables cross-vendor information exchange in the field of industrial automation technology. OPC UA is also known as machine-to-machine (M2M) communication protocol.

OPC UA functionally combines and extends all of the previous OPC specifications from the OPC Foundation. This means that machine data (process values, measured values, parameters, etc.) can not only be transported, but also semantically described in a machine-readable manner.

Another standard for machine-to-machine M2M communication is the message protocol MQTT (Message Queuing Telemetry Transport). In particular, it allows the transmission of telemetry data in the form of messages between devices, e.g. B. from sensors and actuators, mobile phones.

A disadvantage of these known communication standards is that certain functionalities (download, upload, license handling) are not provided. Among other things, OPC assumes a static data model (SOAP XML-based).

In addition, the resource requirements for OPC, among others, are very large, so that with some embedded systems, in particular with simpler sensors or actuators, it is not possible to use OPC and others.

Furthermore, access to data and services across several network nodes, hierarchy levels, topology levels and different network types is sometimes not possible at all or can only be implemented manually with great effort.

In such cases, it is now necessary for every device type to manually integrate the devices into the network.

Usually, sensors transmit data to the controller on request and the controller can write data to the sensors if necessary. Control systems and sensors normally communicate according to the master-slave principle. In the higher levels, the units (network nodes) communicate according to the client-server principle.

However, it is currently not possible to simply display a value from an ERP system on a display.

The object of the invention is to provide a method for accessing data and services of a network node which does not have the disadvantages mentioned above.

This object is achieved by the method steps specified in claim 1. Advantageous embodiments of the invention are specified in the subclaims.

The essential idea of the invention is that each network node presents its data and services in a hierarchical directory structure and each network node can expand its own directory structure through the directory structure of its downstream communication partner.

This enables simple access to data and services across several network nodes, in particular not only from a higher level to network nodes in a lower level, but also in the opposite direction.

The directory structure is quasi expanded from network nodes to network nodes up to the destination network node.

The invention is explained in more detail below on the basis of exemplary embodiments with reference to the drawings.

• 1 Netzwerk der Automatisierungstechnik
• 2 hierarchische Verzeichnisstruktur einer Mastereinheit

They show schematically:

• 1 Network of automation technology
• 2nd hierarchical directory structure of a master unit

1 shows a network of automation technology. The network is structured hierarchically and comprises several different network types 7, 6 and several network nodes.

In the lowest level three field devices (Fieldbus device) are shown z. B. the IO-Link master AL1100 from ifm electronic. Such units can have different units, e.g. B. sensors in particular IO-Link sensors can be connected.

The field devices can also be IO nodes, displays etc.

The master units are connected via a field bus e.g. B. Profibus with a control z. B. connected to a PLC. The control system controls the master units or the connected units.

An edge gateway / router represents the transition from the local network (e.g. the Profibus automation network or the network of a machine / line) to a higher-level network (building network, company network, Internet).

A higher value computing unit z. B. A server / cloud / cluster is connected to one or more EdgeGateways. A lot of individual data come together here.

The higher-value computing units are used for data analysis and z. B. for device management.

The communication channels between the control network and the IT network are shown separately for better understanding. At the lower level, these networks are physically identical.

The field devices and the edge / gateway each have an IOT interface with an interface program IOT. The access to data and services according to the invention takes place via this IOT interface.

In 2nd the hierarchical directory structure of the master unit is shown as an example.

The invention now consists in not only seeing the direct interaction between two devices (network nodes), but also the "penetration" of e.g. to enable higher-value computing unit 3 on a field device 1.

The higher-value computer unit 3 and the EdgeGateway 2 communicate via a similar loT interface program, in which e.g. the EdgeGateway represents its data and services in a hierarchical directory structure (directory tree), just as the field device 1 does in relation to the EdgeGateway 2. Each device has "its tree", which it makes available to the respective layer.

If the EdgeGateway 2 now integrates the tree from the field device 1 into its tree, that is to say “passes on” the IOT interface (IOT interface), the higher-value computing unit 3 can also address these elements using the URLs. The interface from the field device 1 is thus accessible to other network participants through the Edge Gateway 2.

This works even if the communication connections [6] and [7] are different from the network type - without the higher-level computing unit having to be aware of this difference.

Below is a general explanation of how the directory structure of a downstream network node is expanded.
bold - interface of device [2]
Italic - Interface by Device [1]

The IOT interface from Device [2]:
device2 / getidentity
device2 / gettree
device2 / somedata
device2 / somedata / getdata

The IOT interface from Device [1]:
device 1 / getidentity
device 1 / gettree
device 1 / somedata
device 1 / someotherdata / getdata

The IOT interface of device [2] after the integration of the interface of device [1]
device2 / getidentity
device2 / gettree
device2 / somedata
device2 / somedata / getdata
device2 / remote / device 1 / getidentity
device2 / remote / device 1 / gettree
device2 / remote / device 1 / somedata
device2 / remote / device 1 / someotherdatalgetdata

Devices are often used in automation networks in hierarchical structures. As a rule, only one device can be reached directly for configuration / parameterization in such a network.

The invention offers the advantage that all devices can be reached via a standard route.

The IOT interface forwarding only changes the URL of the respective network node, but the entire IOT interface interface remains the same. By organizing the IOT interface in a hierarchical directory structure / element tree (data, services, events), subordinate devices can be easily understood as a sub-directory / sub-tree.

The device responds to the Request Device2 / getidentity which IOT interface version it has.

The device in question1 “knows” that the gettree service is available.

The device2 responds to the request device2 / gettree with its directory structure and possibly with the directory structure supplemented by the directory structure of the downstream network node device3.

With this, the device1 can very easily e.g. Call service with D5 in device3 via a corresponding URL device1 / device2 / device3 / D5.

Simple machine-to-machine communication is possible with the invention.

It is easy to access data and services across several network nodes, in particular not only from a higher level to network nodes in a lower level, but also in the opposite direction. This means that information from the ERP system can also be displayed in a simple manner on a field device.

The directory structure can be expanded or supplemented more and more from network nodes to network nodes up to a target network node.

The invention is particularly suitable for dynamic data models.

Claims (3)

Method for accessing data and services of a network node in a network of automation technology, the network can also comprise hierarchically different network types, wherein each network node has a unique identifier URL, where each network node has a hierarchical directory structure of its data and services each network node having an interface program IOT that allows it each expand its own directory structure by the directory structure of the downstream network node in order to enable data and / or service access. Procedure according to Claim 1 an access from a higher-level computing unit to a field device. Procedure according to Claim 1 an access from a field device to a higher-level computing unit can also take place.

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