CN114513383B - Real-time Ethernet field bus data packet processing method based on original socket - Google Patents
Real-time Ethernet field bus data packet processing method based on original socket Download PDFInfo
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- CN114513383B CN114513383B CN202011277556.7A CN202011277556A CN114513383B CN 114513383 B CN114513383 B CN 114513383B CN 202011277556 A CN202011277556 A CN 202011277556A CN 114513383 B CN114513383 B CN 114513383B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/40—Bus networks
- H04L12/40006—Architecture of a communication node
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/40—Bus networks
- H04L12/40169—Flexible bus arrangements
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
- H04L69/22—Parsing or analysis of headers
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/40—Bus networks
- H04L2012/40208—Bus networks characterized by the use of a particular bus standard
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/40—Bus networks
- H04L2012/4026—Bus for use in automation systems
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Abstract
The invention relates to a real-time Ethernet field bus network data PACKET processing method based on a PACKET_MMAP, relates to the technical field of numerical control, in particular to the technical field of real-time Ethernet field bus, and specifically relates to a real-time Ethernet field bus data PACKET processing method based on an original socket, wherein the original socket adopts the PACKET_MMAP method. Firstly, analyzing a transmission path from a network card drive to a kernel network protocol stack of a real-time Ethernet field bus data packet, and establishing a capturing point of the real-time Ethernet bus data packet at an entrance of the kernel network protocol stack; then, analyzing the characteristics of the data PACKET at the capturing point, and establishing a data PACKET capturing and forwarding method based on the PACKET_MMAP; finally, according to the bus protocol type to which the data packet belongs, a method for analyzing and processing the data packet in the real-time Ethernet bus component in the user space is designed.
Description
Technical Field
The invention relates to the technical field of numerical control, in particular to the technical field of real-time Ethernet field bus, and in particular relates to a real-time Ethernet field bus data PACKET processing method based on an original socket, wherein the original socket adopts a PACKET_MMAP method.
Background
The PACKET_MMAP mechanism is a set of socket programming interfaces based on a memory mapping mode, a kernel buffer area is distributed in a kernel space and mapped to a user space, and then an application program of the user space acquires data mapped to the user space through MMAP system call. The packet_mmap mechanism is very efficient, providing a configurable size ring buffer mapped to user space. In this way, the buffer shared by the kernel space and the user space may also serve to reduce copying of data.
The middle-low grade numerical control system has higher requirement on real-time performance, but is limited by the performance of the system, and the general interpolation period is longer. For cost consideration, the transmission mode of the real-time ethernet fieldbus network data packet is usually implemented in a simple and flexible manner, and the requirement on the transmission time of the network data packet is not so strict. If the packet_mmap mechanism provided by the kernel is adopted to capture the data PACKET at the entry of the network protocol stack, on one hand, no support of a specific network card is needed, and on the other hand, no network card driver and the kernel network protocol stack are needed to be modified, so that the transmission and the processing of the network data PACKET can be simpler and more flexible. Therefore, how to design a simple and efficient real-time Ethernet bus network data PACKET processing method based on a PACKET_MMAP mechanism is a key for solving the real-time and efficient transmission of real-time Ethernet field bus network data PACKETs of a medium-low-grade numerical control system.
Disclosure of Invention
In order to solve the technical problems, the invention provides a real-time Ethernet field bus network data PACKET processing method based on a packet_MMAP.
The technical scheme adopted by the invention for achieving the purpose is as follows:
the real-time Ethernet field bus data PACKET processing method based on the original socket adopts a PACKET_MMAP method, and comprises the following steps:
determining a transmission path from a network card drive to a kernel network protocol stack of a real-time Ethernet field bus data packet according to debugging information output by the kernel, and establishing a capturing point of the real-time Ethernet bus data packet at an entry of the kernel network protocol stack;
according to a real-time Ethernet bus data PACKET capturing point of a kernel network protocol stack entry, a real-time Ethernet bus data PACKET forwarding method based on a packet_MMAP is established, and the real-time Ethernet bus data PACKET is mapped into a real-time Ethernet bus component;
and according to the bus protocol type of the real-time Ethernet bus data packet, analyzing the real-time Ethernet bus data packet in the real-time Ethernet bus component of the user space.
The real-time Ethernet field bus data packet type comprises any one of EtherCAT protocol and SSB-III protocol.
The capture point is located before the real-time ethernet bus data packet is sent to the kernel protocol stack.
The method for establishing the real-time Ethernet bus data PACKET forwarding based on the PACKET_MMAP specifically comprises the following steps:
opening up a static memory for storing real-time Ethernet bus data packets in a kernel space;
shielding receiving interruption generated when the real-time Ethernet bus data packet in the network card is mapped to the annular queue;
reading real-time Ethernet bus data packets in the annular queue into the opened static memory by continuously polling the network card;
at the entrance of the kernel network protocol stack, the transmission of the real-time Ethernet bus data packet to the kernel network protocol stack is shielded;
and mapping the real-time Ethernet bus data PACKET obtained by polling to a user space by adopting an MMAP memory mapping mode of PACKET_MMAP.
The real-time Ethernet bus number is received in an uninterrupted manner.
The real-time Ethernet bus number is read by adopting a polling mode.
The analyzing the real-time Ethernet bus data packet in the real-time Ethernet bus component in the user space specifically comprises the following steps:
establishing user state real-time threads and setting the real-time threads as periodic real-time threads, and completing analysis processing work on real-time Ethernet field bus data packets in the real-time period of each user state real-time thread;
in the beginning part of a real-time thread of a user state real-time Ethernet bus assembly, acquiring a real-time Ethernet bus data PACKET in a polling mode by adopting a PACKET_MMAP original socket;
analyzing an Ethernet protocol data packet header in a real-time thread of the user-state real-time Ethernet bus assembly, and determining the type of the real-time Ethernet bus data packet;
analyzing instruction data of the real-time Ethernet bus data packet according to the type of the real-time Ethernet bus data packet;
organizing the analyzed instruction data into NML neutral message commands, and exchanging data with a real-time application program of a user space through a message communication channel of a user state real-time Ethernet bus assembly;
waiting for the next periodic polling of real-time ethernet bus data packets.
The invention has the following beneficial effects and advantages:
1. the real-time Ethernet field bus adopts a standard network card to transmit data packets, so that the variety structure of the hardware communication board card is effectively reduced. The real-time Ethernet field bus in the existing numerical control system still adopts the traditional communication board card mode to transmit bus data, different field buses (such as EtherCAT, SSB-III real-time Ethernet buses and the like) correspond to different communication board cards, and a set of hardware board card corresponding to each field bus is developed aiming at each field bus, so that the system becomes bulkier and non-reusable.
2. The real-time Ethernet bus data packet is captured and forwarded at the entrance of the kernel network protocol stack, the dependence on the network card drive is avoided, the compatibility is good, and the use mode is more convenient and flexible. The memory mapping mechanism of the PACKET_MMAP is adopted, so that the network data PACKET of the real-time Ethernet field bus protocol is shared to the real-time Ethernet bus component of the user space, and the data PACKET capturing is carried out at the network protocol stack entry without depending on a specific network card, thereby being more convenient and flexible.
3. The real-time Ethernet data packet is received in an uninterrupted manner, so that switching of interrupt contexts is avoided, the data packet processing efficiency is improved, and the system delay is reduced. The control structure of the real-time Ethernet field bus is a master-slave control mode, in the network of the real-time Ethernet field bus, the numerical control system is a master station device for controlling the network, the slave stations are controlled servo drivers, I/O and the like, and the communication of the network is all initiated by the master station, so the master station receives the data packet fed back by the slave stations within a certain time after sending the data packet, and can receive the data packet in a polling mode so as to reduce the context switching caused by interruption.
Drawings
FIG. 1 is a block diagram of a real-time Ethernet Fieldbus network;
fig. 2 is a diagram of a capturing processing method of a data packet.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
The invention is suitable for the field of numerical control systems, in particular for the application occasions of adopting a standard network card to transmit real-time Ethernet field bus network data packets, and is particularly suitable for the application occasions of adopting the standard network card to transmit the real-time Ethernet field bus network data packets in a medium-low grade numerical control system. Specific embodiments of the method of the present invention will be described in further detail below with reference to the accompanying drawings.
The real-time Ethernet field bus network data PACKET processing method based on the PACKET_MMAP comprises the following steps:
1) Determining a transmission path from a network card drive to a kernel network protocol stack of a real-time Ethernet field bus data packet, and establishing a capturing point of the real-time Ethernet field bus data packet at an entry of the kernel network protocol stack;
2) Establishing a network data PACKET forwarding method based on a PACKET_MMAP;
3) According to the bus protocol type of the data packet, designing an analysis processing method of the data packet in a real-time Ethernet bus component of the user space;
the real-time Ethernet field bus is EtherCAT and SSB-III;
the method comprises the steps that a transmission path from a network card drive to a kernel network protocol stack of a real-time Ethernet field bus data packet is determined, and the network card is a network card of any model;
the capturing point of the real-time Ethernet bus data packet is established at the entrance of the kernel network protocol stack and is positioned before the data is sent to the kernel protocol stack;
the method for capturing and forwarding the data PACKET based on the PACKET_MMAP is established, and the PACKET_MMAP uses the programming mode of an original socket;
the method for establishing the data PACKET capturing and forwarding based on the PACKET_MMAP is characterized by comprising the following steps of:
a. opening up a block of static memory in the kernel space for storing Ethernet data packets;
b. the data is received in a non-interrupt mode, and receiving interruption generated by the DMA data packet of the network card to the annular queue is shielded;
c. the data is read in a polling mode, and the data in the annular queue is read into a newly opened memory by continuously polling the network card equipment;
d. shielding the transmission of the data packet to the kernel network protocol stack at the entrance of the kernel network protocol stack;
e. mapping the data PACKET obtained by polling to a user space by adopting a MMAP mechanism of a PACKET_MMAP;
the analysis processing method of the data packet in the real-time Ethernet bus component designed in the user space is characterized by comprising the following steps:
a. establishing user state real-time threads and setting the real-time threads as periodic real-time threads, and completing analysis processing work on real-time Ethernet field bus data packets in the real-time period of each user state thread;
b. in the beginning part of a real-time thread of a user state real-time Ethernet bus assembly, acquiring a real-time Ethernet data PACKET in a polling mode by adopting a PACKET_MMAP original socket;
c. analyzing an Ethernet protocol data packet header in a real-time thread of the user-state real-time Ethernet bus assembly, and determining the type of the real-time Ethernet data packet;
d. analyzing instruction data of the data packet according to the type of the data packet;
e. and organizing the analyzed instruction data into a message command, and exchanging data with an upper-layer motion control component through a message communication channel of the real-time Ethernet component, wherein the upper-layer motion control component is a real-time application program and is used for track planning, acceleration and deceleration control and interpolation calculation.
f. Waiting for the next periodic polling of the data packet.
As shown in FIG. 1, the network structure of the real-time Ethernet field bus based on the packet_MMAP is the left half part of the figure, under the default, a network data PACKET firstly passes through a network card driver and a network protocol stack in the kernel space, then in an application program in the sent user space through an AF_INET socket or an AF_PACKET standard socket, the invention sets a capturing point of the data PACKET at an entrance of the kernel network protocol stack, and directly forwards the EtherCAT and SSB-III real-time Ethernet data PACKETs to a real-time Ethernet bus component in the user space by shielding transmission of the real-time Ethernet bus data PACKET to the kernel protocol stack and adopting an original socket of the packet_MMAP, and the analysis processing is carried out on the data PACKET in the user-state real-time Ethernet bus component.
The data flow structure of the real-time Ethernet field bus based on the PACKET_MMAP is shown in the right half part of FIG. 1, the real-time Ethernet data PACKET is DMA-processed in the real-time Ethernet bus assembly through the network cards to the annular queue inside the original network card driver, the real-time Ethernet bus data PACKET in the annular queue is mapped into the annular queue of the user space through the MMAP mechanism of the PACKET_MMAP in a polling mode, the real-time threads in the upper real-time Ethernet bus assembly read the real-time Ethernet data PACKET in the annular queue through the polling mechanism, the data PACKET is analyzed and processed in the real-time Ethernet bus assembly, and finally, the data is exchanged with the upper-layer motion control assembly through the message communication channel of the real-time Ethernet assembly.
As shown in fig. 2, the capturing processing method of the real-time ethernet field bus data PACKET based on the packet_mmap specifically includes the following steps:
A. static opening up a memory area in the kernel space for storing Ethernet data packets;
B. the data is received in a non-interrupt mode, and receiving interruption generated by the DMA data packet of the network card to the annular queue is shielded;
C. the method comprises the steps that a poll polling mechanism mode is adopted for data reading, and data in a ring queue are read into a newly opened memory by continuously polling network card equipment;
D. at the entrance of the kernel network protocol stack, the transmission of the data packet to the kernel network protocol stack is shielded through shielding the interface of the kernel network protocol stack of the netif_receiver_skb ();
E. mapping the data PACKET obtained by polling to a user space by adopting a MMAP mechanism of a PACKET_MMAP;
F. a real-time thread creation method of RT_Preempt real-time patches is adopted, user state real-time threads are established, the real-time threads are set to be periodic real-time threads, and analysis processing work on real-time Ethernet field bus data packets is completed in the real-time period of each user state thread;
G. in the beginning part of a real-time thread of a user state real-time Ethernet bus assembly, acquiring a real-time Ethernet data PACKET in a polling mode by adopting a PACKET_MMAP original socket;
H. analyzing an Ethernet protocol data packet header in a real-time thread of the user state real-time Ethernet bus assembly, determining the type of the real-time Ethernet data packet, wherein the real-time Ethernet data packet type comprises EtherCAT, SSB-III and other real-time Ethernet protocols respectively;
I. analyzing instruction data of the data packet according to the data packet type, wherein the instruction data of the EtherCAT protocol comprises periodic instruction data and aperiodic instruction data, the periodic instruction data adopts process data of the EtherCAT protocol to carry out data transmission, the periodic instruction data is divided into periodic command data and state data according to different transmission directions, the aperiodic instruction data adopts a mailbox of the EtherCAT protocol to carry out data transmission, and the aperiodic command data and the state data are respectively obtained according to different transmission directions; the SSB-III protocol is similar to the EtherCAT protocol, and the instruction data also comprises periodic instruction data and aperiodic instruction data, except that the SSB-III protocol adopts a mailbox for data transmission for the two data;
J. organizing the analyzed instruction data into message commands, and exchanging data with an upper-layer motion control component through a message communication channel of the real-time Ethernet component;
K. waiting for the next periodic polling of the data packet.
Claims (6)
1. The real-time Ethernet field bus data PACKET processing method based on the original socket is characterized in that the original socket adopts a PACKET_MMAP method, and comprises the following steps:
determining a transmission path from a network card drive to a kernel network protocol stack of a real-time Ethernet field bus data packet according to debugging information output by the kernel, and establishing a capturing point of the real-time Ethernet bus data packet at an entry of the kernel network protocol stack;
according to a real-time Ethernet bus data PACKET capturing point of a kernel network protocol stack entry, a real-time Ethernet bus data PACKET forwarding method based on a packet_MMAP is established, and the real-time Ethernet bus data PACKET is mapped into a real-time Ethernet bus component;
analyzing the real-time Ethernet bus data packet in the real-time Ethernet bus component of the user space according to the bus protocol type to which the real-time Ethernet bus data packet belongs;
the analyzing the real-time Ethernet bus data packet in the real-time Ethernet bus component in the user space specifically comprises the following steps:
establishing user state real-time threads and setting the real-time threads as periodic real-time threads, and completing analysis processing work on real-time Ethernet field bus data packets in the real-time period of each user state real-time thread;
in the beginning part of a real-time thread of a user state real-time Ethernet bus assembly, acquiring a real-time Ethernet bus data PACKET in a polling mode by adopting a PACKET_MMAP original socket;
analyzing an Ethernet protocol data packet header in a real-time thread of the user-state real-time Ethernet bus assembly, and determining the type of the real-time Ethernet bus data packet;
analyzing instruction data of the real-time Ethernet bus data packet according to the type of the real-time Ethernet bus data packet;
organizing the analyzed instruction data into NML neutral message commands, and exchanging data with a real-time application program of a user space through a message communication channel of a user state real-time Ethernet bus assembly;
waiting for the next periodic polling of real-time ethernet bus data packets.
2. The method for processing real-time ethernet fieldbus packets based on an original socket according to claim 1, wherein said real-time ethernet fieldbus packet type comprises any one of EtherCAT protocol and SSB-III protocol.
3. The method of claim 1, wherein the capture point is located before the real-time ethernet bus packet is sent to the kernel protocol stack.
4. The method for processing real-time ethernet field bus data PACKETs based on original sockets according to claim 1, wherein the method for forwarding real-time ethernet bus data PACKETs based on packet_mmap is specifically:
opening up a static memory for storing real-time Ethernet bus data packets in a kernel space;
shielding receiving interruption generated when the real-time Ethernet bus data packet in the network card is mapped to the annular queue;
reading real-time Ethernet bus data packets in the annular queue into the opened static memory by continuously polling the network card;
at the entrance of the kernel network protocol stack, the transmission of the real-time Ethernet bus data packet to the kernel network protocol stack is shielded;
and mapping the real-time Ethernet bus data PACKET obtained by polling to a user space by adopting an MMAP memory mapping mode of PACKET_MMAP.
5. The method for processing real-time ethernet fieldbus packets based on an original socket according to claim 4, wherein the receiving of the real-time ethernet bus number is carried out in an uninterrupted manner.
6. The method for processing real-time ethernet fieldbus packets based on an original socket according to claim 4, wherein the reading of the real-time ethernet bus number is performed by a polling method.
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