TSN (time-sensitive network) is one of the most popular mainstream technologies in industrial communication. TSN standard ensures that periodic data with real-time requirements and non-periodic data without real-time requirements can be transmitted through standard Ethernet facilities, so TSN is also called the future industrial communication standard.
So what's next for the most widely used types of industrial Ethernet?Will TSN replace all real-time Ethernet?The answer is clearly no.TSN is not a disruptive technology that allows existing industrial real-time Ethernet applications to coexist and interoperate.Moreover, most of today's industrial Ethernet technologies are converging with TSN to meet the needs of future industrial communications.
CC-Link is at the forefront of this.
On February 26, the CC - Link association officially released in Beijing for a new generation of network protocol IE passes on cc-link, around the world take the lead in combining gigabit Ethernet bandwidth and passes on, adopt efficient network protocols to further strengthen the performance and function of traditional IE cc-link, expand the IE cc-link based on industrial Ethernet to realize enterprise information layer to application layer from vertical integration of advanced communication technology, to realize the real-time seamless integration of IT and the OT.
Here we take you through the new network protocol.
1 CC-Link IE TSN development background
Are moving in the current manufacturing automation, reduce the comprehensive cost, improve the quality and the direction of many varieties and small batch flexible manufacturing, whether industry 4.0 or the Internet, have a common goal: to build factories "" intelligence, is all the things together, get to make the most of the data, the factory automatic production.
The key to creating an intelligent factory is to collect real-time data from the production process, process IT initially through edge computing, and then transfer IT seamlessly to IT systems.To make full use of the production site data, IT is necessary to be able to carry out high-speed and stable control information communication and transmission of large amounts of information to the IT system network.In other words, the emphasis is on combining industrial networks with IT networks at the production site.
Nowadays, there are a variety of industrial networks, including the requirements for the composition of switches, wiring and other networks. Due to the need to ensure real-time use of different specifications, IT system network and industrial network cannot share the same network and equipment and other topics.At the same time, in order to build an intelligent factory, the high performance and multi-function of the equipment should be used to improve the productivity. At this time, a network capable of high motion control is required, especially in semiconductor, battery manufacturing and other industries, which has a particularly significant demand.
Therefore, it has become an inevitable trend and urgent demand to integrate TSN technology, which realizes real-time performance by time segmentation, into the widely used industrial Ethernet.CC-Link association launched CC-Link IE TSN on the basis of CC-Link IE.
2 CC-Link IE TSN technology implementation
Protocol level: cc-link IE TSN is based on the TSN technology at layer 2 of the OSI reference model. At layer 3 ~ 7, it is composed of cc-link IE TSN independent protocol and standard Ethernet protocol.
TSN consists of several international standards, the main standards are ieee802.1as (definition of time synchronization mode) and ieee802.1qbv (definition of time segmentation mode).The combination of these standards can ensure the timing of transmission in a given time, and can also realize the mixed communication of many different protocols.Standard Ethernet protocols such as SNMP, HTTP, and FTP are also available based on TCP/IP, UDP/IP.
CC-Link IE TSN updated the way of circular communication.The traditional cc-link IE USES the token transfer method, after writing their own data through the token, the site will write the permissions to the next site.By contrast, cc-link IE TSN USES a time segmentation method, which makes use of the synchronization of time in the network to transmit input and output data frames in two directions at the same time within the specified time, thus shortening the update time of cyclic data of the whole network.This method is combined with TSN technology to ensure the coexistence of control information and management information in the same network.This can be interpreted as a change from "one conversation at a time" to "one conversation at a time".
Enrichment profile technology: the cc-link association defines CSP+(control and communication system profile) to make it easier to start, operate, and maintain cc-link family of compatible products.By using CSP+, cc-link IE TSN enhances interoperability with CANopen device profiles.For example, the international standard iec61800-7 (CiA402) can be used to drive the product's communication Settings.
Support general Network diagnosis function: in the cc-link IE TSN Network equipment diagnosis, you can use SLMP(Simple Network management Protocol Simple Network management Protocol), which is widely used in the IT Network monitoring system.Cc-link IE TSN component Information and statistics Information is defined as an extended MIB(Managerment Information Base management Information Base), which can be used for network diagnosis with a common SNMP tool.
3 CC-Link IE TSN four main characteristics
1. Integration of control information communication (real-time) and management information communication (non-real-time)
Cc-link IE TSN gives high priority to equipment control loop communication, and gives priority to bandwidth allocation relative to management information communication, so as to realize the use of real-time cyclic communication control equipment, and at the same time, IT can also simply build a network environment for communication with IT system.In addition, with the coexistence of management data communication, UDP or TCP communication devices can be connected to the same network. For example, high-precision data from visual sensors, monitoring cameras and other devices can be saved for monitoring, analysis and diagnosis.
2. Fast system setup and advanced predictive maintenance
Cc-link IE TSN is also compatible with SNMP, making network equipment diagnosis easier.Up to now, different devices need to use different tools to collect status information. Now, by using common SNMP monitoring tools, we can not only collect and analyze data from cc-link IE TSN compatible products, but also from IP communication devices such as switches and routers.This reduces the time and effort required to start up the system or to verify the running state of the equipment during system management and maintenance.Using the time synchronization protocol of TSN specification, the time difference between cc-link IE TSN compatible devices is calibrated to maintain high precision synchronization.The time information stored in the master and slave stations is synchronized in microseconds. If there is an exception in the network, the running log parsing can be followed up to the exact time of the occurrence of the exception according to the time sequence.This can help identify the cause of the anomaly and restore the network to normal more quickly.In addition, IT can provide IT systems with the status and accuracy of the production site.
3. Maximize the motion control performance and reduce the beat time
CC-Link IE TSN USES time splitting to achieve high speed communication with cycle time of 31.25 mics or less.In the cc-link IE TSN network system, the increase of the number of servo amplifier axes required for control due to the expansion of the production line does not affect the overall beat time, and even greatly reduces the beat time compared with the traditional network system.Cc-link IE TSN will be used together with different performance devices with different communication cycles.Until now, devices connected to the same primary station had to use the same cyclic communication cycle (Link scan time) throughout the network, while cc-link IE TSN could use multiple communication cycles in the same network.This allows devices that require high performance communication cycles, such as servo amplifiers, to maintain their performance while connecting to devices that do not require high speed communication cycles (such as remote I/O devices), at which point the optimal communication cycles are implemented according to the characteristics of each product.It also maximizes the potential of slave station products on the network and improves the productivity of the whole system.
4. Provide more options for equipment suppliers
In the past cc-link IE, in order to give full play to its 1 Gbps bandwidth, the equipment development manufacturers need to use the special ASIC or FPGA hardware to develop the main station or slave station products.Cc-link IE TSN corresponding products can be developed through hardware or software platform.In addition to realizing high speed control by using special ASIC or FPGA hardware, it is also possible to develop master or slave station products by using software protocol stack on general Ethernet chips.The communication speed not only corresponds to 1Gbps, but also corresponds to 100Mbps.By providing equipment developers with a variety of ways (hardware or software) and the realization of optional communication speed (100Mbps or 1 Gbps), equipment developers can choose their own development mode to achieve the development of cc-link IE TSN compatible equipment, while the variety and quantity of compatible products also bring convenience to users.
It is reported that 56 cc-link IE TSN intended cooperative manufacturers, including mitsubishi, will successively launch a full range of products from PLC, motion controller to switch, I/O, servo and robot after spring 2019.
4 cc-link IE TSN typical application scenarios
1. Intelligent factory integrating control data and management information and communication
While ensuring the real-time control of data communication, IT realizes the data communication with other open networks and IT systems in the same network, and builds an intelligent factory.
2. Make full use of common IP communication products and high-performance motion control equipment
In the previous system, the servomotor will stop the servomotor when checking the position, and accurately measure the position of the workpiece through the visual equipment.At this time, the servo amplifier and vision sensor compatible with cc-link IE TSN can be used to synchronize time, and even in the process of moving the workpiece servo motor, the vision sensor can also accurately determine the location of the workpiece.This significantly reduces the beat time.In addition, a large amount of image data obtained from the vision sensor can be transmitted through IP communication, which allows the construction of a network system that reduces wiring without affecting servo control performance.