Faced with these problems, China's Lao Shihe; R's Lao Song started a thorough dialogue, hoping to give you a comprehensive and correct understanding of TSN.
1.TSN means time-sensitive network. What does timeliness mean? Are other networks insensitive to time? Is there a measure?
Answer: To be honest, when TSN was first introduced by B&R headquarters in 20 16, I felt that it didn't seem like a technology in the field of industrial automation, because industrial networks such as PROFINET, POWERLINK and EtherCAT had reached a relatively high real-time index, and there seemed to be few cases that could not be solved in the current cycle of100μ s. The industrial network says "the detector is fuzzy" At that time, I thought that the word was a network developed by IT people who didn't understand the industry, because TSN originally described it as giving Ethernet "deterministic" and "real-time" transmission capabilities, because standard Ethernet didn't have this capability, while real-time Ethernet did.
So, where is the key to the problem? The key purpose of TSN is data transmission in the same network, that is, periodic control communication requirements and aperiodic data transmission are the core requirements of TSN.
Because there is a very big problem in the process of IT and OT integration, that is, periodic data and aperiodic data often need to be transmitted through two networks, so you will find that each controller has two network ports, one is real-time Ethernet and the other is standard Ethernet. Generally speaking, real-time network refers to machine and system control, while standard network is used to transmit management-level information.
Generally speaking, the quality of service (QoS) indicators of a network include period, delay and jitter. Generally speaking, hard real-time will be refreshed to 100 microsecond level, with jitter controlled at tenS of ns level and delay at microsecond level. There is no special official definition of real-time because the application scenarios are different.
2. One of the characteristics of 2.TSN is high real-time. Didn't our previous fieldbus and real-time Ethernet also have this feature? Is there an advantage in real-time performance compared with these TSN?
A: Although the key requirement of TSN is transmission on the same network, the scheduling mechanism designed by R&D personnel also allows high real-time response capability. At present, TSN of Gigabit Ethernet developed by B&R has been tested for 50nS jitter (jitter usually describes the worst case), and the fastest period it can reach is 10μS, so the real-time performance of TSN can be completely guaranteed for existing industrial control.
Compared with the current mainstream real-time Ethernet, TSN has significantly higher performance. According to the gigabit test data of B&R headquarters, the overall performance is improved by 18 times (the test is based on the increasing number of nodes and data load before taking the average performance).
3. How does 3.TSN achieve time sensitivity? Has it changed the standard Ethernet standard?
A: TSN itself is a series of standards, including three key standards: clock synchronization, data scheduling and network configuration. TSN only refers to the standard of data link layer. It must be clear that the physical layer can be realized by using IEEE802.3 Ethernet or IEEE802.3cg standard network, while the data link layer adopts bridging network and different data flow scheduling strategies, namely Shaper- shaper. Such as CBS credit-based shaper, Qbv- time-aware shaper TAS, CQF- periodic queuing and forwarding, ATS- asynchronous transmission shaper. To understand this, you have to understand how Ethernet itself is transmitted, and then understand that TSN mainly designs the strategy scheduling mechanism where transmission is selected.
In the past two years, TSN has become more and more popular in industry. Where does this TSN come from and is it unique to our industry? Are other industries also called TSN? Who is leading this standard internationally?
Answer: TSN is not from industry. TSN was originally in the field of audio and video transmission. Later, in 20 12, IEEE802. 1Q was established in the automobile field, and in 20 15 years in the industry, IEEE802. 1 TSN working group was established.
In the automotive industry, they are generally called AVB- Audio-Video Bridges, which are composed of IEEE802. 1Qav, IEEE802. 1AS and IEEE802. 1Qat (which has been the basic standard of IEEE802. 1Q).
There are also a large number of time-sensitive network applications in aerospace field, which can be called AS6802. In the industrial field, IEC and IEEE cooperated to set up IEC60802 working group, which realized the formulation of TSN network interoperability standard.
At present, organizations promoting TSN are Avnu, including IIC and OPC UA Foundation, which will work with major shaper manufacturers to promote the development of TSN technology.
5.TSN will become the future standard Ethernet protocol, and it is more advanced than the previous standard Ethernet protocol. Does that mean that all future Ethernet protocols used in civil, commercial and industrial fields will become TSN?
Answer: TSN is VLAN technology, that is, the vital local area network, which is clearly defined as local area network and virtual local area network. It doesn't have to be an all-encompassing standard for business and civil use. The difference between TSN domain and non-TSN domain lies in VLANID, that is, VLAN tags will be marked by switches when entering TSN network, and then transmitted in the network by means of TSN mechanism, but will be marked when leaving TSN network. Therefore, there is no problem when TSN switches are used with ordinary switches.
Therefore, the commercial or civil network does not have to be a TSN network, which depends entirely on the requirements of the application itself, especially the economic indicators. Therefore, if there is no special real-time demand, it is unnecessary. At present, TSN network seems to focus on industrial Internet of Things applications.
6. Why did TSN suddenly attract the attention of so many people in the industry in the past two years? Can you solve the problem that can't be solved now?
A: TSN fire is caused by a large number of Internet of Things applications, because you must consider the transmission of periodic and aperiodic data in the same network, and the demand for bandwidth is greater than before.
You can see that in this picture, several scenes are described:
(1) Audio and video synchronization: In fact, if you watch CCTV, you will see that the announcer's mouth and voice will be out of sync-this is also a quality problem, because audio and video are out of sync, or like the speakers of a grand theater. Think about it, if you can't synchronize, there will be repeated sounds, which is also a problem of data transmission quality.
(2).ADAS, compared with traditional cars, ADAS will need multiple laser radars (such as front and rear three), including the safety system. These more sensors will bring greater bandwidth requirements than before.
(3).AR/VR, machine vision: More application of these technologies in industrial scenes will increase the demand for bandwidth.
Therefore, TSN has practical needs, and the connection becomes more extensive, requiring greater network capacity transmission capacity.
7. Since time-sensitive Ethernet has so many advantages, why didn't you consider making it time-sensitive when launching an earlier standard Ethernet? Why add time sensitivity now? Did you not think of it at first, or the original technology could not be realized, or the cost was too high? ,
A: When Volkswagen came to China to invest and build factories in the 1990s, expressway, China had just started, including many old residential areas with insufficient parking spaces. Who would have thought that cars are so popular today?
By the same token, when you don't need this technology, you won't really have the motivation to develop it, because if no one uses it, these R&D investments will lose their meaning. Therefore, the popularization of any technology takes time. Moreover, TSN has not really broken out at present, because the demand for interconnection has just begun in recent years, and a large number of factories are actually still in the stage of stand-alone production. Therefore, TSN is now in a precautionary stage, because the application of big data only started locally, rather than entering an outbreak period.
Of course, you are right. To realize a network like TSN, it really needs a lot of technical input, because its complexity exceeds the existing network. Just as clock synchronization has more reliability requirements than IEEE 1588, the scheduling mechanism is more flexible. These all need chip processing, including gigabit Ethernet processing chips, transmission cables, switching chips and so on. These are all costs, and only in the face of huge market opportunities will chip manufacturers have the motivation. Now a large number of chip manufacturers are investing in it, because they see its broad future-these investments will make TSN easier to use and cheaper-and the potential scale of TSN makes it more competitive than the previous network.
8. So far, what's the latest development of TSN's related product development, test bed and supporting manufacturers?
A: At present, TSN has several important test bed promoters, one is the test bed organized by German LNI-Industry 4.0, and the other is the test bed organized by Huawei ECC. B&R actively participated in the test bed construction of the three organizations.
At present, mainstream automation manufacturers have released their own TSN products or test products, such as B&; R 2065 438+07 released TSN products in SPS, Siemens 20 18 released Profinet over TSN products in Hanover, and Mitsubishi 20 19 released CC-Link IE TSN products. Huawei, TTTech, Cisco, MOXA, hessman and other manufacturers also released TSN switch products.
9. Although TSN is very popular in the past two years, almost everyone is optimistic about its support, why are there not many actual products, or there is no mass production and sales, and there is almost no formal industrial application? Where is the main card? When is TSN expected to be really applied?
A: It seems that you are more anxious than users. However, the life cycle of industrial products is generally long, just like CAN bus and Modbus which are still in use. It's not as slow as you think. Compared with the past bus in terms of concept, local application and large-scale mature application, TSN has developed rapidly, because you should know that TSN's industrial working group was established at the end of 20 15. Shaper's mobilization meeting was held in September, 20 16, so it was very fast for you to see so many companies launch products in 20 18.
TSN will launch mass products on 20 19, including B&R and Mitsubishi. Industrial products will not be updated as quickly as mobile phones. Before I bought Huawei's P20 Mate Pro, the P30 came out. The general life cycle of industrial products is more than 15, because a machine tool may be used for more than 20 years.
So, in fact, TSN has developed rapidly.
10. What equipment does a communication network need to realize TSN? Will the implementation cost of TSN be higher than other networks?
A: TSN is a VLAN, so many of its implementations are at the software level. It needs a switch to handle this clock synchronization and scheduling mechanism. Of course, for the controller, TSN chip support is needed, and I haven't considered the specific chip cost yet. But the law of things development is * * *, and the cost must be a process of decline, because a large number of applications can reduce the cost.
1 1. Now TSN products from foreign manufacturers have been released one after another, but not from domestic manufacturers. How to develop a master station or slave station or I/O for TSN? Is the cost high?
A: Not exactly. Huawei has been ahead in this respect, and their TSN switch has been developed. However, it seems that it has not yet entered the mass production stage, because Huawei will consider more scene problems, so it will have some of its own designs on the shaper. Recently, I wrote TSN shaper and invited two experts from Huawei to teach it. In addition, MOXA also has TSN switch products.
At present, XILINX, TTTech and Intel*** have provided TSN technology development boards, and chip manufacturers NXP and AD have also launched TSN development test chips and test boards.
12. Now real-time Ethernet and fieldbus are widely used in control field, especially in motion control field. Will TSN replace these protocols? What is the relationship between TSN and these real-time networks?
A: It needs to be emphasized again that TSN is in the second layer of ISO/OSI architecture, which means TSN can appear in various forms. In fact, Ethernet itself is also a development process. For example, Profinet is Profibus over Ethernet and POWERLINK is CANopen over Ethernet. Scenes such as Profinet on TSN and CC-Link IE on TSN will appear. This design is often to maintain the continuity of application software and ensure the availability of existing equipment investment, while B&R will choose OPC UA instead of TSN. The original POWERLINK CANopen application layer will gradually turn to OPC UA, and it is necessary to maintain the continuity of a software application. This is also a process in which the application layer will maintain and the data link layer will gradually turn to TSN for a long time. Judging from the current performance of TSN, there is no problem in dealing with the task of motion control. Some manufacturers Xuancheng will soon launch TSN motion control products, B&R will launch IO and controller on 20 19, and it is planned to launch motion control products based on TSN communication in 2020.
It must be emphasized that for any industrial application, it is necessary to maintain the stability and inheritance of technology. Therefore, the upgrade of technology must be as smooth as possible, as well as for users, which is the guarantee of investment security. Therefore, TSN will definitely not replace the existing network in the short term, but in a longer period of time, TSN will become the basic network architecture.
The ISO/OSI model is very interesting, that is, it allows each layer, including the physical layer, to be designed independently. The current IEEE802.3 can continue to be used. Of course, physical layers such as PoE(Power onEthernet) and SPE (Single Pair Ethernet-IEEE 802.3 CG) can also be used.
13. Now another communication technology, 5G, has arrived. 5G also has the characteristics of low latency and high bandwidth, and its most important application may be in industry. Will TSN and 5G be competitive?
A: There is a scene of ULL(UltraLower Latency) in 5G, but it belongs to a wireless network and should not be used in industrial applications, especially those similar to motion control. However, in IIoT-based applications, it is possible to use 5G in areas where network deterministic evaluation can be tolerated. In addition, TSN will have a standard for wireless scenarios.
Therefore, the application prospect of evaluation technology mainly depends on the scenario-they will definitely not be competitive, but complementary.
14. For TSN, some people think that it is "much cry and little rain". What's the latest development of TSN standard? What other problems need to be solved to speed up the progress? With the rapid development of technology, will TSN be replaced by new communication technology halfway?
A: In fact, the core driving force of any technology is "economy". The promotion of technology must have an acceptance process and the market needs to be cultivated. Therefore, TSN obviously cannot be widely used in a short time. Considering that the field bus has actually gone through 30 years from the beginning to the peak, if we look at the development of the whole industry, the development speed of TSN from 20 15 to today is very fast.
As for whether TSN will be replaced by new communication technology, this question is very interesting. In theory, anything is possible, but any technology comes from demand. If there is no essential change in demand, then there will be no essential change in technology. If the demand is the unification of the network, then both TSN and a new technology are the same path to realize this technology, and communication technology cannot exist independently without chips and industrial control. So TSN can't exist independently.
The development of technology has its inevitability. Now that we have seen the technical requirements after 10 and developed TSN, it will continue to develop for a long time.
As for what will happen in a longer time, such as 30 years, I think most people will not pay attention to it, because at this time, if you keenly observe the network demand in 30 years, and then develop the technology to be used in 30 years, then your company will not survive.
15. If TSN is popularized in all fields in the future, is it the so-called industrial Internet of Things?
A: This is worth looking forward to. TSN is committed to this. However, it is not necessarily that everything must be interconnected through TSN, because there are too many technologies in this world, just like the 5G mentioned just now. Humans are interesting because of diversity and worth exploring because of the unknown. It doesn't matter whether TSN can realize the Internet of Everything. It's just a technology and doesn't need to be given such great significance. Just as Bill Gates said, "We always overestimate what we can do in one or two years, but underestimate what we can do in five or ten years"-TSN does not seem to be widely used in the short term, but in the long run, TSN will occupy a dominant position in the fields of automobiles and industrial Internet, but its best partner is OPC UA, and the cooperation between them will make it possible for industry to be unified in the world.
Of course, in the industrial world, the creation of value depends not only on network technology, but also on the pursuit of customer value, including the application value of software and human creativity. Without these, TSN can do nothing, it is just a tool to realize our value creation process-for industrial enterprises, value still comes from solving problems for customers, and TSN will help us.