Network communication methods

Abstract

Method for transmitting data communication between two communication participants (2) connected to each other in a network (1) via a network connection (3), wherein the network connection (3) is connected to a network interface (4) of the communication participant (2), wherein the network interface (4) is configured to transmit data via an MII interface (8) of the communication participant (2) or to receive data via an MII interface (8) of the communication participant (2), wherein the MII interface (8) is a media-independent interface that transmits or receives data regardless of the type of network connection (3), and wherein the following procedure is carried out for transmitting the data communication in the network interfaces (4): a) Sending the data communication; i) Receiving the data communication (23) of the sending communication participant (2) from the MII interface (8) of theCommunication participant (2); ii) Receiving application-specific status and control information (25); iii) Completely converting the data communication (23) into a data stream with a format suitable for transmission over chip-to-chip connections; iv) Incorporating the status and control information into the data stream; and v) Sending the data to the receiving communication participant (2) via the network connection (3); b) Receiving the data communication: i) Receiving the transmitted data via the network connection (3); ii) Extracting the application-specific status and control information (25); iii) Completely converting the data communication back to its original format; iv) Outputting the status and control information (25) to the application logic; and v) Passing the data communication (23) to the MII interface (8) of the communication participant (2), wherein the network interfaces (4) in which steps a) and b) are performed are provided by other microcontrollers orThe communication endpoints (5) of the communication participant (2) are independent.

Description

State of the art Ethernet transmissions, including fieldbuses such as EtherCAT, are predominantly transmitted via twisted pair connections. Ethernet is a technology that specifies software and hardware for wired or data-line-based data networks. Originally intended for local area networks (LANs), Ethernet enables data exchange in the form of data frames between devices connected to a local network. The Ethernet protocol includes specifications for cable types, connectors, and transmission methods (i.e., definitions for signals at the physical layer and packet formats). In the OSI model, Ethernet is the data link layer (OSI Layer 2). In the IT sector, for example with regard to personal computers, Ethernet has become established and proven as a standard in network technology. Industrial applications have specific requirements for data transmission between participants in a data network, which limit the suitability of classic Ethernet. This is particularly true because Ethernet networks require special measures to prevent data transmission collisions, which often result in excessive effort and costs. The physical transmission (Layer 1 of the OSI model) is usually carried out using a transmission technology adapted to the transmission medium. In the case of Ethernet, these are standardized, for example, as 100Base-TX. To transmit data to a network participant using this standard, the data must be prepared accordingly for the respective physical transmission standard, the "physical interface." This is often done using an integrated circuit (IC) called "Ethernet PHY" or simply "PHY." This IC is usually connected via a standardized interface for the data (MII, medium independent interface) and also has an MDI (medium dependent interface), which is primarily used for configuration. Typically, only the data from the MII interface is transmitted. The configuration performed via the MDI interface controls how the data is transmitted but has no influence on the content. A "Phy" is an integrated circuit designed and suitable for encoding and decoding data for transmission over a physical medium. It receives signals on the MII interface and converts them into the appropriate format for the respective transmission path. Decoding the signals is particularly complex, as the PHYs are designed to compensate for distortions caused by long data lines. This typically results in long latency and comparatively high power consumption, which is converted into heat. Since a PHY is required for each connection, the PCB space required and the component costs are also significant if a PHY must be used between the MII interface and the transmission path in every case. The media-dependent transmission technology LVDS is generally advantageous for connections within an assembly or between two directly connected assemblies. LVDS stands for "low voltage differential signaling." LVDS is a signaling standard designed for direct communication between integrated circuits on a printed circuit board or for backplane communication. LVDS is a common transmission standard frequently used in standard ICs. LVDS is characterized by the fact that it does not use the voltages common in digital systems, such as 3.3 volts, but rather significantly lower differential voltages between two wires. The use of differential transmission increases the robustness of the transmission while simultaneously reducing electromagnetic emissions. Furthermore, the lower voltage levels reduce the required charging currents, thus minimizing power loss at both the transmitter and receiver. A common challenge in signal transmission, including via LVDS, is ensuring that the signals transmitted from the physical plane as voltage level differences are correctly sampled as data at the receiver. This can be achieved either by transmitting a clock signal in parallel with the data, requiring an additional wire pair, or by implementing a clock recovery method from the transmitted signal. These latter methods exist in various forms. In principle, there is a need for transmission technologies that can replace and supplement Ethernet within modules or in the direct connection between two modules, and which may use LVDS to enable physical data transmission via data lines. Disclosure of the invention This describes a method for transmitting data communication between two communication participants connected to each other in a network via a network connection, wherein the network connection is connected to a network interface module of each communication participant, and further application-specific signals are transmitted by the communication controller, and wherein the following procedure is carried out in the network interface modules for transmitting the data communication: a) Sending the data communication: i) Receiving the data communication of the sending communication participant from the communication interface of the communication participant; ii) Receiving application-specific status and control information; iii) Complete conversion of the data communication into a data stream with a format for transmission over chip-to-chip connections;iv) Introducing the status and control information into the data stream; v) Sending the data to the receiving communication participant (2) via the network connection; b) Receiving the data communication: i) Receiving the transmitted data via the network connection; ii) Extracting the application-specific status and control information; iii) Completely converting the data communication back to its original format; iv) Outputting the status and control information to the application logic; and v) Passing the data communication to the communication interface of the communication participant, wherein the network interfaces in which steps a) and b) are performed are independent of any other microcontrollers or communication endpoints of the communication participant. Steps a) and b) with their respective substeps i), ii), iii), iv) and v) are each executed in the network interfaces (4). The network interfaces (4) in which steps a) and b) are executed are independent of other controllers (5) of the communication participant (2). In this way, it is possible for the other controllers of the communication participants to communicate with other communication participants or their controllers via so-called MII interfaces (MMI = medium independent interface). From the perspective of the procedure described here, the communication interfaces mentioned in step a) i) and in step b) v) are the communication endpoints. The communication interfaces are preferably media-independent interfaces (MII interfaces) that provide or receive data regardless of the type of network connection. Network communication preferably takes place according to the Ethernet standard. It is particularly advantageous if each network interface is configured so that it can be used either as a receiving network interface or as a sending network interface, so that data communication can be sent in both directions in the network. Furthermore, it is advantageous if, in addition to the communication data, further application-specific status and control data are transmitted in the data stream in parallel to or within gaps between the communication data. The method described here makes it possible in a particularly simple way to implement media-independent data transmission and simultaneously integrate application-specific status and control information into the data stream on the sender side and extract it again on the receiver side, without impairing the media-independent data transmission. Application-specific status and control data are preferably data relating to the hardware of the respective communication participant and its operation. This can include, for example, data concerning the hardware's condition, enabling error diagnosis, or data containing information about the hardware utilization of the respective communication participants. Such data can be exchanged, for example, to communicate errors or error sources within the communication network or to perform load balancing. The term "application logic" describes the hardware of the respective communication participants. It is also advantageous if processing of the data communication includes at least one of the following processing measures: - Step b) ii): Reading data from the data communication, - Step a) iv): Writing data into the data communication. Furthermore, it is advantageous if each network connection consists of exactly four physical lines, with two lines dedicated to each direction of communication. These two lines form a differential line pair for LVDS transmission. It is particularly advantageous if, in step ii), the network interfaces each undergo coding and / or encoding that ensures the absence of DC voltage in a signal transmitted over the network connection. It is also advantageous if the encoding and / or encoding in the network interfaces is performed using a 4b5b decoder and / or a 4b5b encoder. Furthermore, it is advantageous if the encoding and / or coding in the network interfaces is performed according to Manchester encoding. Furthermore, it is advantageous if the network interfaces each allow for the sending and receiving of data from the network connection lines using differential data transmission. This document describes a novel transmission technology that can be used at Layer 1 of the OSI model, thus enabling media-independent transmission for various applications. This novel transmission technology comprises a physical transmission technology and logic that allows for flexible deployment of the physical transmission technology by the user. The use of LVDS becomes possible. Furthermore, several advantages can be achieved, namely high robustness, low electromagnetic radiation, and low energy consumption for data transmission. The goal is to enable a direct connection between two participants, each equipped with an Ethernet MII interface (or a variant such as RMII, RGMII, etc.). This eliminates the need for an additional physical connection, thereby saving PCB space, BOM costs, latency, power consumption, and heat dissipation. At its core is a logic that, on the one hand, exchanges the data via the MII interface (a media-independent interface between level 2 and 1 of the OSI layer model) of the network participant and then transforms it so that it can be exchanged via a direct connection to another communication partner. Additional application-specific status and control data can be transmitted, either in parallel with the data packets or in gaps between the data packets. This direct connection between two participants (also called an "IC-to-IC connection") can be established, for example, via LVDS. Alternatively, the connection can also be established via a bus (possibly via a backplane or a switch). The method described here encodes the signal in such a way that clock recovery can occur on the other end, allowing the MII signal, as well as the status and control data, to be fully restored. Thus, no additional clock line is required. Clock recovery is preferably achieved using various methods, such as the described 4b5b encoding or Manchester encoding. The described network interfaces for this method thus enable the replacement of the standard physical Ethernet connection between two network participants with a simple channel based on standardized microcontroller logic signals. This conversion is transparent to the higher transmission layers in the described network interfaces for this method. It is also advantageous if, for the conversion of the data communication, a clock recovery is performed from the data communication received from the network connection, which makes it possible to assign data in the data communication. At the same time, the chosen encoding allows for easy clock recovery on the receiver side. The clocks of the two participants do not need to be synchronized. The communication interfaces can be implemented, for example, as standard logic in FPGAs (FPGA = Field Programmable Gate Array). An FPGA is a programmable logic device on which the circuitry of the communication interfaces can be individually configured. For each connection between two participants, there is a transmission channel for sending (TX) and one for receiving (RX). The connection is configured such that the TX output of one participant is connected to the RX input of the other participant, and vice versa. Each participant preferably has two transmission paths: one to the preceding participant ("left") and one to the following participant ("right"). Because of this direct point-to-point connection between sender and receiver, the data is not transmitted over a shared medium, so collisions cannot occur when accessing the medium and therefore do not need to be considered. If LVDS is chosen as the transmission standard, the data is transmitted via four lines: two for sending (TX) and two for receiving (RX). The network interfaces described here are located between the media-independent interface and the lines of the network connection. The standard 4b5b encoding is used, as is also used in standard Ethernet. Data is transmitted using predefined data codes. Special control codes have various functions: 1.) The receiver can be synchronized to the data stream: Using bit patterns that never occur in the normal data stream, the receiver can synchronize to the data stream, recognize the 5-bit word boundaries, and only pass on valid words for 4b5b decoding. 2.) A signal can be sent indicating that no data is currently being transmitted. 3.) A signal can be sent when the connection is established on the receiving end ("Link Up"). 4.) Additional application-dependent control and status information can be transmitted. As previously mentioned, alternative data encodings for the data stream can include, for example, 4b5b encoding or Manchester encoding. These encodings increase the symbol rate compared to the original bit rate of the data stream; in the case of Manchester encoding, this increases to 200% of the original bit rate. State signaling and synchronization with the data stream are achieved by using illegal transitions to indicate the start of a packet. In the case of 4b5b encoding, the symbol rate is increased to 125% compared to the original bit rate. The functionality of the sending and receiving communication interfaces is explained in detail below for 4b5b encoding. Sender: The transmitter receives signals from the MII interface of the network interface. This data is first 4b5b encoded. Control codes are generated during 4b5b encoding, if necessary. The output signal of the 4b5b encoding is serialized and transmitted over the transmission line. The symbol rate is 125% of the original bit rate due to the 4b5b encoding. For example, Manchester encoding also uses an encoding logic whose data is serially output. Recipient: On the receiver side, the clock and bit stream must first be reconstructed. This is done using clock detection, whose logic reconstructs the bit stream. The start of the 5-bit values ​​can be detected using the synchronization control signals. These 5-bit values ​​are then passed to the 4b5b decoder, which outputs the signals accordingly via the MII interface of the network interface. This section will also describe a communication participant that is set up to carry out the described network communication. Furthermore, a network comprising at least two communication participants will be presented here. The described method and the technical environment are explained in more detail below with reference to the figures. Figure 1 shows a network set up for the described method, Figure 2 shows two adjacent communication participants in the network with a network connection, Figure 3 shows a transmit module of a network interface of a communication participant, and Figure 4 shows a receive module of a network interface of a communication participant. Figure 1 shows an example of a network 1 consisting of three communication participants 2, each connected to the other by network connections 3. Each communication participant 2 has two network interfaces 4 to which the network connections 3 are connected, so that the network 1 is structured in a series in which the communication participants 2 are arranged. This can be described as a linear or serial arrangement of the communication participants 2 in the network 1. Data communication is possible in this network 1 along the series in two directions 6. However, the method and network interfaces 4 described here are also applicable in networks 1 with only two communication participants 2 and only one network connection 3 between these communication participants 2. Fig. 2 illustrates the interaction of two adjacent communication participants 2 in the network. The two communication participants 2 and the network connection 3 through which they are connected are shown. The network connection 3 is connected to network interfaces 4 of each communication participant 2. The network connection 3 has two individual lines 7, each of which is intended for communication in one direction 6. Each communication participant 2 has at least one controller 5 configured to perform the tasks for which that communication participant 2 is intended.Between network interfaces 4 and the controller 5, there exists an internal media-independent interface 8, through which data received via network connection 3 is transmitted to the controller 5, independent of the properties of network connection 3. The network interfaces 4 are configured to perform all necessary adjustments, conversions, and / or encodings of data required for transmission via network interface 4. From the controller 5's perspective, the data received by or sent via the media-independent interface 8 is independent of, or unaffected by, the physical properties of network connection 3. Each network interface 4 has a transmit module 9 and a receive module 10, wherein a transmit module 9 of one network interface 4 is connected to a receive module 10 of another network interface 4 via a line 7. In Fig. 2, it is also shown that the right-hand communication participant 2 has two network interfaces 4, so that another communication participant 2 can be connected to it via another network connection 3. Fig. 3 shows a transmission module 9 in detail. The data is transmitted by the controller 5 via a media-independent interface 8 or an Ethernet interface 20 of a controller 19 with an encoder 17. The encoder 17 encodes the data and then forwards it to a serializer 15 for serialization. The media-independent data 23 thus become a data stream 26. The serializer 15 operates with a clock signal provided by a clock generator 11. The data is then forwarded as a bit data stream 22 to an LVDS transmission module 13 via line 7 of the network connection 3. Control information 25 from an application logic 21 can be included in the data stream 26 via the controller 19. Fig. 4 shows a receiver module 10. The data is received as a bit data stream 22 from a line 7 of the network connection 3 by an LVDS receiver module 14 and then fed to a deserializer 16. From there, the data is sent to a decoder 18. Decoding is performed using a clock signal, which is detected by the clock 12 from the signal received via line 7 of the network connection 3. After decoding by the decoder 18 and a controller 19, the data is transmitted to the microcontroller 5 via the media-independent interface 8 or an Ethernet interface 20. The data stream 26 is then decoded by the decoder 18 into media-independent data 23. The controller 19 can also extract control information 25 from the data stream 26 and pass it to an application logic 21. Reference symbol list 1 Network 2 Communication participant 3 Network connection 4 Network interfaces 5 Controller 6 Direction 7 Line 8 Media-independent interface 9 Transmit module 10 Receive module 11 Clock generator 12 Clock detection 13 LVDS transmit module 14 LVDS receive module 15 Serialization 16 Deserialization 17 Encoder 18 Decoder 19 Control 20 Ethernet interface 21 Application logic 22 Bit data stream 23 Media-independent data 24 Time clock 25 Status and control information 26 Data stream

Claims

Method for transmitting data communication between two communication participants (2) connected to each other in a network (1) via a network connection (3), wherein the network connection (3) is connected to a network interface (4) of the communication participant (2), wherein the network interface (4) is configured to transmit data via an MII interface (8) of the communication participant (2) or to receive data via an MII interface (8) of the communication participant (2), wherein the MII interface (8) is a media-independent interface that transmits or receives data regardless of the type of network connection (3), and wherein the following procedure is carried out for transmitting the data communication in the network interfaces (4): a) Sending the data communication; i) Receiving the data communication (23) of the sending communication participant (2) from the MII interface (8) of theCommunication participant (2); ii) Receiving application-specific status and control information (25); iii) Completely converting the data communication (23) into a data stream with a format suitable for transmission over chip-to-chip connections; iv) Incorporating the status and control information into the data stream; and v) Sending the data to the receiving communication participant (2) via the network connection (3); b) Receiving the data communication: i) Receiving the transmitted data via the network connection (3); ii) Extracting the application-specific status and control information (25); iii) Completely converting the data communication back to its original format; iv) Outputting the status and control information (25) to the application logic; and v) Passing the data communication (23) to the MII interface (8) of the communication participant (2), wherein the network interfaces (4) in which steps a) and b) are performed are provided by other microcontrollers orThe communication endpoints (5) of the communication participant (2) are independent. Method according to claim 1, wherein each network interface (4) is configured to be used optionally as a receiving network interface (4) or as a sending network interface (4), so that data communication can be sent in the network (1) in both directions (6) of the network connection (3). Method according to one of the preceding claims, wherein each network connection (3) is formed by exactly four physical lines (7), wherein two lines (7) exist for each direction (6) of communication. Method according to one of the preceding claims, wherein in step iii) in the network interfaces (4) an encoding and / or decoding takes place which ensures that a signal transmitted on the network connection (3) is free of DC voltage. Method according to claim 4, wherein in the network interfaces (4) the decoding and / or encoding is performed using a 4b5b decoder and / or a 4b5b encoder. Method according to claim 4, wherein the decoding and / or encoding in the network interfaces (4) is carried out in accordance with Manchester coding. Method according to one of the preceding claims, wherein in the network interfaces (4) a transmission and a reception of data from lines (7) of the network connection (3) with differential data transmission takes place. Method according to one of the preceding claims, wherein for the conversion of the data communication a clock recovery from the data communication received from the network connection (3) is carried out, with which an assignment of data in the data communication is possible. Network interfaces (4) configured for operation according to a method according to one of the preceding claims. Communication participant (2), with at least one network interface (4) according to claim 9 . Network (1) comprising at least two communication participants (2) according to claim 10.

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