Patent Application
20230336380
The present invention relates to a method of operating a network, in particular an automation network.
The method is intended to be usable for integrating components of an automation network into an existing multifunction network, for example into an Ethernet network, in particular into a fieldbus network designed as an Ethernet bus.
In existing automation networks, such as SERCOS III, there is often the restriction that devices of the automation network are the sole users of the network. And although the automation network is also designed as an Ethernet network, it is not trivial to integrate such an automation network into an existing network.
These difficulties consist of restrictions, for example in terms of network topology, which make integration into other networks difficult or impossible.
A SERCOS III automation network, for example, is based on sum frame telegrams in the form of Ethernet broadcasts without VLAN tag. It therefore requires a specific network topology, such as ring or line topology, with a stable subscriber sequence.
Since the maintenance of such an order cannot be guaranteed when integrating such nodes into an existing Ethernet network according to the IEEE specification, such integration is difficult or impossible.
A correspondingly known communication in an automation network is known, for example, from WO 2018/215209 [U.S. Pat. No. 11,336,657]. Here, the devices are mainly connected in a line topology and enabled by corresponding communication through data telegrams.
In order to also provide data nodes in an automation network, for example in order to be able to make the subscriber sequence more variable, a method for transmitting telegrams in an automation network is known from DE 10 2018 129 809 [US 2021/0281666]. However, the topology that connects the devices to the automation network is also fixed here.
Last, a further method for routing telegrams in an automation network is known from DE 10 2019 114 309 [U.S. Pat. No. 11,411,769], where a further diversification of nodes in the automation network is made possible. However, even according to this reference, an arbitrary combination of different network topologies and an integration of an automation network in an existing network is not possible.
Thus, it is an object of the present invention to integrate an automation network into an existing network and to facilitate the use of multiple network topologies that interconnect the devices or subscribers of the network.
This object is attained by the features of the main claim.
A method is thus proposed for operating a network comprising at least one switch. The switch serves as a node in the network and can send or receive data in all directions of the node. Furthermore, the switch includes programmable logic that can store and use the relationships to the other nodes in the network.
Also, the network contains at least two terminals and a controller. The controller is also referred to as the master in an automation network.
According to the invention, the controller can send data to a specific terminal via an application protocol in order to control it. The application protocol is implemented via the application layer of the OSI network model. This means that communication via the application protocol is implemented in OSI layer 7.
In accordance with the specification for Internet networks, the data sent in this way is divided into data packets and sent via the network's link layer. This means that the individual data packets are transmitted as frames within the link layer, i.e. layer 2 of the OSI model. For this purpose, according to the invention, an additional address is added to the data packets within the link layer so that the data packets can reach the desired destination and be addressed to it.
The switch can thereby recognize this additional address and/or ensure the transmission to the addressed terminal by adding the address. Optionally, the controllers can also recognize and/or add the additional address.
Before transmission to the addressed terminal, the additional address of the data packets is deleted again, so that the original data packets are restored from the data originally sent to the terminal.
By adding the additional address and also sending the data packets within the link layer, a selection of the addressed network nodes can be carried out. This means that the data packet does not have to be sent to all devices by means of a broadcast command, but a preselection is made. This preselection makes it possible to implement different network topologies connected to the switches and still ensure communication in the automation network.
The addition of the additional address can be done by the controller itself or by the switches used in the network. Removing the additional address can then also be done by the switches or the controller.
One possibility of the additional address is the identification of a communication relationship and assignment of a VLAN, as used for example from the “Mask & Match” method (IEEE 802.1CBdb). This function first identifies a communication relationship between the addressed terminal and the controller or a switch and thus limits the number of addressed terminals. By assigning a VLAN, the request is then only sent to a limited part of the terminals in the network.
Another possibility for the additional addressing medium is a multicast, unicast or broadcast to only certain MAC addresses in the network. For this purpose, each terminal, each switch and also each controllers has a fixed MAC address that is known to the switch. Accordingly, the request can be sent to only a limited number of terminals with a certain circle of MAC addresses. This procedure is called “active Destination MAC” and is known from IEEE 802.1CB.
As a third option of the additional address, VLAN tags can also be used that are assigned depending on the egress port neighbor. These VLAN tags are also added to the data packets. This option assigns a VLAN to a specific group of terminals and thus addresses them.
In addition to these three possibilities for the additional address, it can also be a source address. The address of the sender (source) is used for this. Also, an Ether type as defined in IEEE 802.3 can be used. Furthermore, a bit mask is conceivable as an additional address that is placed over a part of a data packet, preferably over the first bytes of a data packet.
Last, a combination of the above methods can be used for the additional address.
By these designs it is possible to create a virtual network for the communication in the automation part of the network that works according to the normal communication rules of the automation network. The real network can be branched or composed of several topologies. The communication protocol of the automation network then works with the virtual network and can also only address this. This design then makes it possible to operate an automation network as part of another network without having to restrict or reprogram the function of the automation network.
The switches should be located at the nodes of the networks, preferably between the controller and the terminals. This means that different topologies can be interconnected in a network starting at these nodes.
The terminals of the automation networks can be connected in series, in a ring or in a line, depending on the topology. This also corresponds to the normal function of an automation network. In principle, several automation networks can thus be connected together in a network by the switches so that subscribers who do not belong to the automation network can also be part of the same network.
The method according to the invention includes the step of the terminals also responding according to the automation network and the application protocol, so that the response can be sent from the terminals to the corresponding controller. The method functions similarly to the method described above, so that here too an additional address is added to the data packets within the link layer and the data packets are sent to the terminal, for example the controller, via the link layer. Here, too, the additional address is deleted again before transmission to the addressed terminal.
The advantage of this method is that only the virtual network is visible to the application protocol, thus enabling the normal application commands for the automation network. The real network can be structured differently by the switches, so that an almost arbitrary combination of automation networks and normal network is possible. The combination of different topologies is also possible.
Preferably, it is suggested that controller and terminals are parts of an automation bus. This bus is then operated as an automation network with Ethernet specification.
Preferably, it is proposed to configure the controller and/or the switch by a network management that is preferably software, to be able to perform the desired progression of data from a network subscriber to the terminal.
The controller and the terminals are taken from an automation network. However, the terminals 20, 21 are included in a different network strand than the terminal 22. The terminals 20, 21 are in a line topology and the terminal 22 in a ring topology.
There may be other network nodes located on the branches of the network, but these are not shown in this
The branches or different topologies are connected by two switches 30, 31. Accordingly, the switches 30, 31 represent nodes in the network that connect the different branches or topologies.
If the controller 40 now wants to send data for controlling a terminal to, for example, terminal 20, corresponding data is sent to the network via the application protocol. The application protocol is executed in the application layer of the OSI network model.
According to the specifications of an Ethernet network, this data is now divided into data packets and sent via the link layer (OSI model layer 2) according to the invention.
For this purpose, an additional address is added to the data packets 1 and sent. The addition can be done via the controller 40 or via the switch 30.
The additional address defines a group of subscribers in the network that is then addressed. This means that not all nodes in the network are addressed via a broadcast, as is usual in an automation network, but only some of the nodes, for example nodes of a specific branch in the network.
In the present case, an additional address is now added to the data 1 in order to address the terminal 20. For example, the request is sent to the subscribers 20, 21 of the upper branch of the network in
The request first reaches terminal 21 that, however, is not addressed by the additional address and is forwarded as shown at 7 to terminal 20. Here, the address and the specific destination match, so that terminal 20 accepts and converts the data.
Before reaching the terminal 20, however, the address is deleted according to the invention. After evaluating the address, the switch can reach the two terminals 20, 21 via a multicast without requiring the additional address.
The switches 30, 31 are at the nodes of the network and connect the individual branches of the network. The branches in turn can be designed in different topologies.
As a result, it is now possible to integrate automation networks into conventional Ethernet networks.
The present application is not limited to the previous features. Rather, further embodiments are conceivable. For example, instead of at least one switch, a router or a server could be used. Also, more than two switches and/or controllers could be used.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 12. 275.6 | Sep 2020 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/074223 | 9/2/2021 | WO |
