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The advantage of using wireless data transmission module... Data transmission can be simply divided into two major types: wired (including the installation of optical cables, cables or leased telecommunication lines) and wireless (including the establishment of dedicated wireless data transmission system or the borrowing of CDPD, GSM, CDMA and other public network information platforms).     In...

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Industrial-grade 4G router TCP/IP network architecture 1. Layering of TCP/IP network system   TCP/IP (TransmissionControlProtocol/InternetProtocol), transmission control protocol/Internet protocol. It was developed by the defense advanced research projects agency in the 1970s, and was later integrated into UNIX and popularized. It emerged in the 1980s as the Internet's...

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The structure of 4G DTU The main function of DTU is to transmit data from remote devices back to the background center via wired/wireless. Different data transmission modes of DTU include all-network-connected DTU, GPRS DTU, WIFI DTU, CAN DTU and 4G DTU. Today, we will have a look at the structure and work flow of DTU.   To complete...

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What are the wireless connection technologies of the... Internet of things (iot) applications have been deeply rooted in our lives. The E-Lins H685 industrial-grade router is a small industrial-grade wireless router with single or double LAN ports. TDD/ fdd-lte, 4G, 3G, GPRS network optional. Besides, what are the wireless connectivity technologies for the Internet of things?   1....

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The use of industrial wireless routers Industrial-grade wireless router adopts high performance 32-bit industrial-grade ARM9 communication processor, which is widely used in finance, electric power, postal, water conservancy, environmental protection, meteorology and other industries.   Industrial router is mainly used in intelligent transportation,...

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Industrial-grade 4G router TCP/IP network architecture

Category : 技术相关

1. Layering of TCP/IP network system

 

TCP/IP (TransmissionControlProtocol/InternetProtocol), transmission control protocol/Internet protocol. It was developed by the defense advanced research projects agency in the 1970s, and was later integrated into UNIX and popularized. It emerged in the 1980s as the Internet’s communications protocol. With the continuous growth of the Internet, TCP/IP protocol also continues to develop, not only in the wide area network is widely used, in the LAN industry 4G wireless router TCP/IP protocol has replaced other protocols and become widely used protocol. Nowadays, TCP/IP protocol has become a common and universal network interconnection standard.

 

 

TCP/IP protocol is a layered protocol developed by the industrial 4G wireless router based on the OSI reference model.

 

 

The TCP/IP protocol hierarchy is basically designed according to the OSI reference model. Only in three layer on the layers of the TCP/IP protocol to the application layer of the OSI reference model, the presentation layer and session layer and unified into a single application layer, so that the 4 g industrial router function such as the representation of a data format, the establishment of the session and application software more closely together, compared with the OSI reference model is more practical and simple. Although we used to call the industrial GPRS router TCP/IP protocol, in fact it is not a single protocol, but a set of protocols, called the industrial CDMA router TCP/IP protocol family.

 

 

In the TCP/IP protocol family, each protocol is responsible for a part of the network data transmission and provides some aspect of the service for data transmission in the 4G router network. It is because of these protocols that work at all levels that the entire TCP/IP protocol family can effectively work together.

 

 

2. The characteristics and advantages of TCP/IP network system

 

 

In the long-term development process, 3G wireless router IP gradually replaced other networks. Here’s a simple explanation. 3G router IP transmits common data. Data can be used for any purpose and can easily replace data previously transmitted over proprietary data networks. Here’s a common process:

 

 

A proprietary network is developed for a specific purpose. If it works well, users will accept it.

 

 

To facilitate the provision of IP services, they are often used to access E-mail or chat, often through proprietary network tunneling in some way. The LTE router tunneling approach may initially be very ineffective.

The structure of 4G DTU

Category : 技术相关

The main function of DTU is to transmit data from remote devices back to the background center via wired/wireless. Different data transmission modes of DTU include all-network-connected DTU, GPRS DTU, WIFI DTU, CAN DTU and 4G DTU. Today, we will have a look at the structure and work flow of DTU.

 

To complete the data transmission needs to establish a complete data transmission system. In this system includes: DTU, customer equipment, mobile network, background center. On the front end, DTU is connected to the customer’s device via a 232 or 485 interface. Therefore, DTU alone cannot complete the wireless transmission of data, and it needs to be used together with background software. After establishing the connection, the front-end equipment and the back-end center can conduct wireless data transmission through DTU, and the transmission is two-way. The new generation of DTU has developed to varying degrees in terms of simple data collection, multimedia display and data processing.

 

GPRS DTU communication

 

GPRS DTU working process:

After GPRS DTU is powered on, it first reads the working parameters saved in internal FLASH (including GPRS dialing parameters, serial port baud rate, data center IP address, etc., which have been configured in advance).

 

GPRS DTU logs on to GSM network and then does the GPRS PPP dialing. Upon successful dialing, GPRS DTU receives an internal IP address (typically 10.x.x.x) randomly assigned by the mobile. That is, GPRS DTU is in a mobile Intranet, and its Intranet IP address is usually not fixed and changes with each dial. We can understand that GPRS DTU is a mobile internal LAN device, through the mobile gateway to achieve communication with the external Internet public network. This is similar to how a computer in a LAN accesses an external network through a gateway.

 

GPRS DTU initiatively initiates the communication connection with the data center and maintains the communication connection. Because GPRS DTU is in the mobile Intranet, and the IP address is not fixed. Therefore, only GPRS DTU can actively connect to the data center, and not the data center can actively connect to GPRS DTU. This requires the data center to have a fixed public network IP address or a fixed domain name. The public network IP address or fixed domain name of the data center is stored as a parameter in GPRS DTU, so that once GPRS DTU is powered up and successfully dialed, it can be actively connected to the data center.

 

Specifically, GPRS DTU initiates TCP or UDP communication requests to the data center through parameters such as the IP address of the data center (if the domain name of the data center is adopted, the IP address of the data center will be resolved through the domain name of the data center) and port number. Upon receiving the response from the center, GPRS DTU is deemed to have successfully shaken hands with the center, and then the communication connection is maintained. If the communication connection is interrupted, GPRS DTU will immediately shake hands with the center again.

Now that the TCP/UDP communication connection has been established, data two-way communication is possible.

 

GPRS DTU application

 

Wide application of DTU:

DTU has been widely used in electric power, environmental protection, LED information release, logistics, hydrology, meteorology and other industries. Although the application industry is different, but the principle of the application is the same. Most of them are connected with industrial equipment, such as PLC, SCM and other automation products, and then establish wireless communication connection with the background. Today, with the development of the Internet, DTU is more and more widely used. It provides help for the information and industrial integration among various industries. It has also gradually developed into the core technology of iot application.

What are the wireless connection technologies of the IoT

Category : 技术相关

Internet of things (iot) applications have been deeply rooted in our lives. The E-Lins H685 industrial-grade router is a small industrial-grade wireless router with single or double LAN ports. TDD/ fdd-lte, 4G, 3G, GPRS network optional. Besides, what are the wireless connectivity technologies for the Internet of things?

 

1. Ethernet

 

Ethernet is a LAN communication technology. The IEEE 802.3 standard, organized by the IEEE, establishes the technical standard for Ethernet. It specifies the content of the protocol including the connection of the physical layer, the electronic signal and the media access layer. Ethernet USES twisted pair cables as the transmission medium, which can cover up to 200 meters without relaying. The most popular Ethernet types have data transfer rates of 100Mb/s, while newer standards support rates of 1KMb/s and 10KMb/s.

 

The biggest advantage of Ethernet technology is that it is the most commonly used LAN technology and has gradually replaced other LAN standards such as token ring, FDDI and ARCNET. Now we are familiar with the Internet is all these large and small LAN connected together, the formation of a global network.

 

2. Serial communication technology

 

Serial port is a very generic interface for communication between devices and is also widely used for communication between devices and instrumentation. Common serial ports are rs-232 (using 25-pin or 9-pin connectors) and semi-duplex rs-485 and full-duplex rs-422 for industrial computer applications.

 

Serial communication USES serial mode for communication, that is, the serial port sends and receives byte sequences by bit. Typically, the serial port is used for the transmission of ASCII characters. Serial communication USES three wires: ground wire, sending and receiving. The serial communication can use the sending line to send data and the receiving line to receive data at the same time.

 

(1) Advantages

 

The biggest is a bit high penetration rate of serial communication, serial port to a PC or a standard, usually in order to convenient to connect printers, most of the industrial equipment has a serial port, who do not have a serial port devices, in its development, the common method is developed through a serial port to connect to the computer, so a serial port equipment is most simple and easy way to communicate.

 

It is also worth mentioning that the cost of serial communication is very low if the cable connecting the serial port is not considered.

 

(2) Disadvantages

 

The networking ability of serial port communication is poor. Although it is usually more stable than wireless, it is also vulnerable to the electromagnetic influence of the environment in which the cable is located in the industrial environment, resulting in unstable communication or even burnt out serial port. Serial Ethernet is still a long way off, and is generally only suitable for low speed and small data volumes.

 

3. Modbus

 

Unlike the previous communication technologies, Modbus is generally regarded as an application-layer protocol standard for serial communication, and does not include electrical specifications. Modbus was originally published by Modicon in 1979 for the use of programmable logic controller (PLC) communication. Later, three modes of Modbus RTU, Modbus ASCII and Modbus TCP were derived. The first two physical interfaces are the serial ports described above, and the latter one USES the Ethernet interface.

 

With the extensive application of PLC in the industrial field, Modbus has also become the most popular communication protocol in the industrial field. It adopts Master/Slave communication mode, namely one-to-many connection. One Master controller can support up to 247 Slave controllers.

 

(1) Advantages

 

The main advantages of Modbus are:

Standardization, open, free use, no license fee, no intellectual property authorization.

Supports a variety of electrical interfaces, such as serial and Ethernet interfaces, and a variety of transmission media, such as twisted pair, optical fiber, wireless, and so on.

 

The frame format of Modbus protocol is simple, compact and easy to understand. Easy to develop, easy to use.

 

(2) Disadvantages

Modbus mainly has the following problems:

Poor networking capability, only master – slave communication

Network size is limited by the number of slave controllers with poor security, no authentication and no permission management, plaintext transmission is very risky in an uncontrolled environment

 

4. GPRS

 

GPRS stands for General Packet Radio Service. GPRS is a long communication technology between a terminal and a communications base station.

 

Radio services first adopted analog communication technology, which became the first generation of Mobile communication technology, and later adopted digital communication technology, known as the second generation of Mobile communication technology. Among them, Global System for Mobile Communications (GSM) is the most widely used and most successful. GSM is designed primarily for the transmission of voice, voice in transmission, exclusive a channel.

 

GPRS can be said to be a continuation of GSM. It transmits data in packet mode and does not monopolize channels. Therefore, idle channel resources on GSM can be better utilized. The transmission rate of GPRS can reach 56~114Kbps. Using this data service, users can connect to the communication base station of the telecom operator, and then connect to the Internet to obtain Internet information. Launched by the European telecommunications standards commission (ETSI), GPRS was handed over to the 3rd Generation Partnership Project, or 3GPP.

 

(1) Advantages

 

Because the coverage of GSM network signal is very wide, in fact, the area where GPRS service can be used is also very wide, which is the main advantage of GPRS technology.

 

Secondly, the GPRS terminal can roam freely within the signal coverage, and the developer does not need to develop any other communication equipment (the operator is responsible for it), which is convenient for users.

 

Finally, due to the popularity of mobile communication terminals, their costs have been greatly reduced. Therefore, the adoption of GPRS communication technology in the Internet of things has a greater advantage over Wi-Fi or ZigBee in hardware cost.

 

(2) Disadvantages

 

GPRS terminals use the infrastructure of telecom operators when communicating, so they have to pay a certain fee, namely data traffic fee, which limits a large number of devices to connect to the network.

 

The lower rate of GPRS is another problem.

GPRS communication quality is greatly affected by signal strength, and the communication effect is poor in areas without signal coverage or weak, which may affect the completion of service.

 

5. NFC

Near field communication Near field communication NFC is a short-range high-frequency radio technology, which belongs to the RFID technology. Its working frequency is 13.56MHz and its effective working distance is within 20cm. The transmission speed is 106Kb/s, 212Kb/s or 424Kb/s. Data is read and exchanged through card reader and point-to-point business model.

 

NFC was first developed in 2002 by Philips semiconductor, Nokia and SONY. In 2004, NFC BBS was established, dedicated to the standardization and promotion of near-field communication technology.

 

(1)     Advantages

 

NFC communication distance is very short, but the communication confidentiality is good.

 

NFC card no power consumption, card reader power consumption is low, can be applied to a lot of no power consumption, or low power application scenarios.

 

The cost of NFC solutions is low, especially the cost of NFC CARDS is very low, especially suitable for covering a large number of non-intelligent objects.

 

NFC communication technology is currently widely used in mobile payment and consumer electronics. For example, many mobile phones already support NFC applications, and micropayment systems such as bus CARDS all use NFC technology.

 

(2) Disadvantages

 

The NFC does not carry the risk of eavesdropping on the wireless signals of other wireless communications, but the simplicity of its NFC card and the design of its passive response are also factors of insecurity. The risk of seeing reports: that the transaction information in an NFC card, for example, could easily be read by other card readers, or even a smartphone.

 

In addition, short communication distance and low communication rate are also its disadvantages, which limit the NFC to be only suitable for certain iot applications.

 

6. LoRa

 

LoRa comes from the word Long Range, which is a communication technology for long-distance communication. LoRa technology, based on linear Chirp spread spectrum modulation, continues the low-power characteristics of FSK modulation, but greatly increases the communication range. Chirp spread spectrum modulation has long distance transmission and good anti-interference performance, and has been used in military and aerospace communications for many years. In extreme cases, LoRa’s single gateway or base station can cover an entire city or tens of kilometers.

 

(1) application scenarios of LoRa

 

Typical scenarios for LoRa applications include very long battery life (a few years), long-distance communication between nodes, and low rates (such as just a few data transfers per hour). As with NB-iot, low power metrics can be sacrificed to increase speed.

 

Cascade and stack of industrial-grade 4G routers

Category : 技术相关

The most basic star Ethernet architecture, the actual star enterprise network may be much more complex than this. This renaturation is not only reflected in how high-end network equipment, how complex configuration, more importantly, the performance of network switching level is more complex. Industrial routers and firewalls in enterprise networks typically require only one, but industrial 4G routers are usually more than one (except for small networks with around 20 users). If you have a large number of users, say hundreds or even thousands, you will have to rely on cascading or stack extension connections from industrial-grade routers.

 

But cascading and stack technologies are also different, and their scope of application is different. Industrial 4G router cascade refers to the expansion of the whole network router and the whole network connection router through switching ports, which not only solves the problem of insufficient port number of a single industrial LTE router, but also solves the connection between the client and network equipment far away from the computer room. Because single-segment switched double-stranded Ethernet cables can reach 100 meters, each cascade of industrial-grade LTE routers can extend the distance by 100 meters.

 

However, this does not mean that it can be arbitrarily cascade, because the line is too long, on the one hand, the attenuation of the signal on the line is more, on the other hand, after all, the lower the level of industrial network router or sharing a port available bandwidth of the superior switch, the more the level, the lower the available bandwidth of the final client will be (although you may be using a 100-megabyte industrial network router), which has a great impact on the network connection performance, so from a practical point of view, it is recommended to deploy the industrial router of the whole network at most, that is, the core industrial router – second level industrial router – third level all-network router.

 

The level 3 here does not mean that only three industrial level full netcom routers can be allowed, but only three levels from the level. The ports used for hierarchical connection can be specialized UpLink ports or ordinary switching ports. Some full-netcom industrial routers have dedicated cascading (UpLink) ports, but some don’t. If there is a specialized cascading port, it is best used because its bandwidth is usually wider than that of a normal switching port, further ensuring the bandwidth of a lower-level, all-network-enabled, industrial-grade router. If not, it can only be cascaded through normal switching ports.

The difference between 4G router and 4G DTU

Category : 技术相关

4G industrial wireless router and 4G DTU are also used for wireless network data transmission of industrial equipment. But there are also significant differences between the two, and the differences between the two are mainly from the appearance of the interface, the use of methods and the application environment.

 

1. Appearance interface the appearance interface of 4G router usually has a network port, which provides wireless networking functions for the network port devices and requires the network port devices to actively access the center to complete data transmission. In general, 4G router will provide a variety of network interface modes of WAN port, LAN or freely switched WAN/LAN port, which can be customized to match the interface according to the connection mode in the project.

 

The external interface of 4G DTU generally only provides the networking mode of serial port interface. 4G DTU is mainly used for two-way transmission between serial port data and IP data. And some projects need to use both the network port, but also need to use the serial port how to do? In the current era of rapid technological development, 4G router and 4G DTU function have been integrated.

 

2. Methods 4G router can be used to convert Ethernet and fieldbus communication protocols. Only the IP address specified by 4G router needs to be set in the terminal device as the gateway. If the specified IP address (or the specified IP address segment) is not set, the communication function cannot be implemented. The primary purpose of 4G DTU is to achieve dial-up, not gateway in the real sense. For example, 4G DTU can be used as a new network device after dialing into the terminal device, and the terminal device address can use this 4G DTU binding address.

 

3. 4G router in the application environment usually has VPN/APN function and private network encryption. In addition, industrial 4G router with WIFI function is suitable for outdoor WIFI wireless signal coverage projects and similar public transport WIFI and mall WIFI sharing projects. However, 4G DTU is applied in the field terminal with scattered transmission distance and high data communication rate, so the real-time performance of 4G DTU can meet the requirements of most industrial fields and is usually used for data acquisition and monitoring system. Such as charging pile remote monitoring system, environmental monitoring system, real-time monitoring of energy consumption, dam water conservancy project monitoring application.

 

4. Data access interface of terminal equipment

4 g router provides one network interface of data access, terminal equipment needs only the IP address of the mouth to the 4 g router in the network as a gateway to the IP address of the terminal device must use specified or specify the IP address in the address period, 4 g router to specify the server hostname or IP address of the IP address of the server host for data exchange, and all the other 4 g router is not set between the address of the can’t communicate.

 

5. 4 g DTU data access generally also provides a serial port or network interface, but their use is used to dial, not used to do in the true sense of the gateway, such as serial interface 4 g DTU after completion of the access terminal dial-up, 4 g DTU as terminal equipment of a new network equipment, terminal equipment address using the new network equipment binding address; The 4G DTU of the network interface is similar to the ADSL of telecommunications, which requires the device to complete a dial-up action.

 

6. IP address used by the terminal device

The IP address used by terminal devices using 4G routers is any IP address that can be set by itself or in the IP address segment, which is also different from the IP address assigned by the UIM card.

The IP address used by terminal devices using 4G DTU is generally the IP address assigned by UIM card dialing (which is specified by 3A).

 

7. Transmission security of terminal equipment

Terminal devices using 4G routers must use the specified IP address, and any other address cannot communicate. After the data of the terminal device passes through the 4G router, the content transmitted through the wireless network is encrypted. Generally, the data transmitted in the intercepted wireless network cannot be decrypted, and the encrypted data can only be decrypted correctly by the designated communication server. At the same time, there is a unique corresponding serial number and other key processing for all data. 4G router guarantees that the terminal device data will not be replayed or resent.

Using 4 g DTU terminal device using IP address would not have such restrictions, so just can assign IP addresses can and to communicate with the server system, terminal equipment data after 4 g DTU, use the wireless network to transmit the contents of the general only through IP head processing, intercept wireless network transmission of data simply remove header information can speak transmission data display; At the same time, the data are not processed accordingly. 4G DTU may lead to the replay or retransmission of wireless data, which will lead to abnormal system, thus causing potential security risks.

 

8. Wireless access security

Using 4 g router data exchange is using a wireless router and communication between the server to establish the safety of the tunnel, all of the data exchange can be to end (terminal) to end (server), and any other middle to end data are cannot communicate effectively, that is to say, at the ends of the wireless network provider will not be able to enter any system.

4G DTU data exchange USES the data exchange process within the wireless network provider, which enables the wireless network provider to easily access any system at both ends of the communication.

 

9. Anti-interference of terminal equipment

Core system USES 4 g router is embedded operating system, only can use very little data port, and the relationship between the terminal equipment is only a routing, so terminal equipment cannot reach the other end, even not be able to access other terminal equipment of the same type, even if there is a terminal device is controlled by a virus or by an outsider, is only affect the a terminal device, the other is not affected.

Terminal devices using 4G DTU are related to 4G DTU and can easily access other terminal devices. If one terminal device is controlled by a virus or an outsider, all terminal devices and the central server system will be seriously threatened.

 

10. Equipment status monitoring

4G router can monitor the status at the same time, and basically know where the problem is and the corresponding solutions through log information.

When using 4G DTU, the status monitoring cannot be carried out, so when encountering problems, it will take much trouble or trouble to check.

 

11. server network routing Settings

When using 4G router to access the terminal device, it is necessary to add a 4G router from the server to the terminal device and use the communication server as the gateway, thus reducing the complexity of the network.

When using 4G DTU to access the terminal device in the server, it is to add a route to the terminal device in the server with the access interface of the wireless network provider as the gateway (or related route).

 

12. Anti-interference of server network

When using 4G router, the data transmission must conform to the preset regulations, otherwise, the communication cannot be carried out correctly, reducing the possibility of unnecessary network traffic. At the same time, according to the sent serial number and other key processing, to ensure that the server data will not be replay or resend.

4G DTU does not carry out relevant filtering during data transmission, so other machines can directly send some illegal information to the device terminal through the network. Meanwhile, 4G DTU increases unnecessary network traffic. At the same time, the data is not processed accordingly, which may lead to the replay or retransmission of wireless data, which will lead to the abnormal system, thus causing security risks.

 

13. Data compression and transmission

4G routers can compress large packets before transmitting, thus reducing network traffic, increasing network bandwidth and improving data transmission efficiency (except for images and images with high compression ratio).

4G DTU generally does not compress data during data transmission.

 

14. Processing of exchange data

Communication server is the core of 4G router, so there must be one host installed on the center server side for 4G router to communicate with. All data exchanged between devices must be encrypted, decrypted, verified and routed by it. There are no other intermediate servers in 4G DTU, but directly connect to the center server.

Characteristics and differences between RS485 and RS232

Category : 技术相关

RS232 and RS485 have always been the weak current common interface, but there are a lot of people do not understand the difference between them is not very thorough.

 

I. overview of RS485

 

RS-485 serial bus is widely used when the communication distance is tens of meters to thousands of meters. RS-485 adopts balanced transmission and differential reception, so it has the ability to suppress common mode interference. In addition, the bus transceiver has high sensitivity and can detect voltage as low as 200mV, so the transmission signal can be recovered from kilometers away.

 

The RS-485 operates in a semi-duplex mode, with only one point in the sending state at any time. Therefore, the sending circuit must be controlled by the enabling signal.

 

II. Features of RS485

 

The RS-485 is very convenient for multipoint interconnection and eliminates many signal lines. The RS-485 enables networking to form a distributed system that allows up to 32 parallel drivers and 32 receivers. In view of the shortcomings of RS-232-C, the new standard RS-485 has the following characteristics:

(1) the electrical characteristics of RS – 485: The voltage difference between the two lines ( +6V ~ +2V) represent the logic “1″, the voltage difference between the two lines (-6V ~ -2V) represent logic “0″. The interface signal level is lower than RS-232-C, so it is not easy to damage the interface circuit chip, and the level is compatible with TTL level, making it easy to connect with TTL circuit.

 

(2) The maximum data transmission rate is 10Mbps

 

(3) RS-485 interface adopts the combination of balanced driver and differential receiver, and has strong anti-common mode interference ability, that is, good anti-noise performance.

 

(4) The maximum transmission distance standard value of RS-485 interface is 4000 feet(about 1219meters), which can reach 3000 meters in fact.

 

(5) RS-232-C interface is only allowed to connect to one transceiver on the bus, that is, single station capability; The RS-485 interface is only allowed to connect up to 128 transceivers on the bus, that is, it has multi-station capability, so that users can use a single RS-485 interface to easily establish the device network.

 

III. Overview of RS232

 

The RS-232 interface conforms to the interface standard for serial data communication formulated by EIA. The original number is EIA- RS-232 (short for 232, RS232). It is widely used in computer serial interface peripheral connection. Connect cables and mechanical, electrical characteristics, signal functions and transmission processes.

 

The RS-232-C standard specifies data transfer rates of 50, 75, 100, 150, 300, 600, 1200, 2400, 4800, 9600, 19200 baud per second.

 

IV. Features of RS232

 

RS-232 is one of the main serial communication interfaces. Due to the early appearance of RS232 interface standard, it is inevitable that there are some deficiencies, mainly including the following four points:

 

(1) The interface signal level value is high, easy to damage the interface circuit chip. RS232 interface any signal line voltage is negative logic. That is, logic “1″ is -3 — -15v; Logic “0″ : +3 — +15V, noise tolerance is 2V. That is, the receiver is required to recognize the signal higher than +3V as the logical “0″, and the signal lower than -3v as the logical “1″. TTL level of 5V is the logical positive and 0 is the logical negative. It is not compatible with TTL level, so it needs to use level conversion circuit to connect with TTL circuit.

 

(2) The transmission rate is low, and the bit rate is 20Kbps in asynchronous transmission; Therefore, in 51CPLD development board, the comprehensive program baud rate can only be used 19200, which is also the reason.

 

(3) The interface USES a signal line and a signal return line to form a common ground transmission form, which is easy to generate common mode interference, so the anti-noise interference is weak.

 

(4) The transmission distance is limited. The standard value of the maximum transmission distance is 50 feet, which can only be used for about 15 meters in fact.

 

V. Application field

 

RS-232 is now commonly used in short distance transmission data rate is low, can work effectively in a noisy environment, such as factories, public site, etc., the commonly used equipment has a low-speed modem, industrial control equipment, programmable logic controller (PLC), computer numerical control (CNC) machine tools, robots, embedded control computer, medical instrument and equipment, and embedded controller development system.

 

RS-485 is commonly used in long-distance transmission with high data transmission rate. The commonly used equipment includes point-of-sale terminals (POS), measuring instruments and large specialized automatic machines.

 

But in a normal application, we often need to convert between two different interface types. At this point, we can use the popular USB interface, which can help us to switch to RS-232 interface and RS-485 interface.

 

In conclusion, RS-232 is suitable for short distance and low-speed transmission, while RS-485 is suitable for long distance transmission. RS-485 is a new interface standard aiming at the shortcomings of RS-232 interface. Because of its good anti-noise interference ability and multi-station ability, it has become the preferred standard.

What is M2M?

Category : 技术相关

As is known to all, besides providing more broadband speed and quality, 5G is characterized by the application of the Internet of things (IoT) from the demand and design stage. In order to adapt to different applications, mobile communication technology with no wiring, high coverage and high reusability has become an important carrier.

 

However, there are still considerable difficulties to be solved in the communication between objects, such as how to reduce the impact of a large amount of M2M communication on existing communication networks, and how to avoid increasing the complexity of network operation and maintenance. Therefore, the development of M2M will play an extremely important role in 5G in the future. So what is M2M?

 

I. brief introduction of M2M technology

 

M2M(MachinetoMachine), is the effective control of devices through mobile communication, so as to greatly expand the boundaries of business or create a more efficient way of doing business than the traditional way or create a completely new service completely different from the traditional way. In short, M2M refers to the information exchange and transmission between machines, which achieves the concept of information sharing through the transmission and link of network and communication between machines and devices.

 

In fact, as early as 2002, the concept of M2M business has been proposed, but due to the immature communication technology, the development is still in the enlightenment stage, such as tap water, power company’s automatic meter reading and digital home application. With the rapid development of wireless communication technology, the application of M2M services into the stage of rapid development, in agriculture, industry, public security, urban management, health care, public transportation, and environmental monitoring, can see M2M applications, such as: Integration of smart energy saving, smart car, smart medical care, smart city, smart logistics and other services and applications, very dependent on M2M technology development.

 

II. Application category of M2M

 

Due to the rapid take-off of the Internet of things industry, it is more necessary to integrate the unified and standardized M2M technology. At present, a considerable number of international standards organizations have invested in the research of M2M standardization, including ITU-T, ETSI, IETF, IEEE, 3GPP, OMA, Zigbee and other alliances. According to the research direction and focus of each standard organization, M2M international standard organization can be divided into the overall architecture category, perception extension category, network extension category and business application category. The specific contents of each category are as follows:

 

Overall architecture class

 

M2M business system architecture

Conduct standardized research on M2M requirements, point-to-point architecture, identity analysis, network management and security, etc. Typical standard organizations include ITU-TSG13, ETSITC SmartM2M, OneM2M, CCSATC10, etc.

 

Perceptual extension class

 

Perception layer of M2M module market

Some low transmission rate and short distance wireless communication technologies are standardized, including short distance wireless communication technology, sensor network and telecommunication network fusion, and lightweight IPv6 technology. Typical standard organizations include IEEE802.15, IETF6LoWPAN, CCSATC10, Zigbee alliance, etc.

 

Network communication

 

M2M network communication

The transformation and optimization of M2M hosted network are carried out. Related technologies include the increase of wireless connection network, core network enhancement, environmental awareness, heterogeneous network fusion, etc. Typical standard organizations include itu-t, 3GPP, CCSATC5, IETF, ETSI, etc.

 

Business application class

 

Standardized for enterprise application, public application, cross-enterprise application and application intermediary software platform, the key application fields include smart transportation, smart home, smart power grid, health care, etc. Typical standard organizations include IETF, CCSATS10, ETSI, OGC, etc.

 

III. Industrial application of M2M

 

In the field of application, M2M module technology often combines the sensor to collect information, and through the sensor’s exploration of the unknown environment, the obtained information is transmitted to the device or device, and the available information has been analyzed. In the industry, real-time feedback information can be collected to ensure the quality of products and avoid the failure of equipment parts. According to the desired purpose, the information needed will be probed to improve the accuracy and safety of people’s lives.

 

For example, M2M combined with sensors, applied in industrial process monitoring, can help the machine reduce downtime and timely diagnose potential problems, and provide timely notification and warning in case of failure before affecting the operation of the machine. Improve machine efficiency by monitoring machine performance and making appropriate adjustments. It is also about reducing maintenance costs and increasing the number of devices produced, because you know and react immediately, and you can access information, communicate and calculate at any time.

 

In the factory production process and automation process maintenance, is an indispensable role. Because most of the machines in the factory will inevitably encounter the possibility of defects and loose falls, the process monitoring and adjustment to avoid the machine, because of the loose falls and reduce productivity. Knowledge of information can be gathered through instant messaging in return, and data can be retroactive through access and file creation to facilitate the life cycle of machines and products.

 

IV. Differences between M2M and the Internet of things

 

M2M is a point, or a line. Only when M2M is scaled and popularized, and intelligent integration and communication are realized between each other through the network, can the “Internet of things” be formed. Therefore, the scattered and isolated M2M is not the Internet of things, but the ultimate goal of M2M is the Internet of things. Communication show this year, there are a lot of M2M applications and display, such as China mobile phone wallet and mobile phone power purchase business, China telecom’s “silent e” business, and China unicom “wireless environmental testing platform” business, belong to M2M applications, you can say it is to belong to the category of the concept of Internet of things, but is not the Internet of things. Therefore, to realize the real Internet of things, it needs massive addresses, massive bandwidth and massive storage, as well as extremely high communication intelligence and management intelligence, as well as very perfect regulatory regulations to ensure the feasibility of business.

 

Looking at the current development of M2M, with the development of science and technology, it can be expected that more and more devices have the ability to communicate and network, realize the application of environmental monitoring, environmental analysis and so on, and create Internet of things business opportunities. M2M and the Internet of things will be the focus and direction of future industry development, it will completely change the work and lifestyle of the whole society, the Internet of things is not a dream!

The similarities and differences between industrial 4G router and industrial switch

Category : 技术相关

1. definition of industrial 4G router and industrial switch

 

Industrial 4G router:

 

Industrial 4G router is a network device responsible for path finding. It provides users with communication by finding the least communication from multiple paths in the interconnection network. Industrial 4G router has two typical functions: data channel function and control function. The functions of data channel include forwarding decision, backplane forwarding and output link scheduling, etc. The control function is usually implemented by software, including information exchange, system configuration and system management between the router and the neighboring industry 4G router. Industrial 4G routers are used to connect multiple logically separate networks. The industrial 4G router USES the routing table to select the path for data transmission. The routing table contains the list of network addresses and the distance between each address. The industrial 4G router USES the routing table to find the correct path of the packet from the current location to the destination address. The industrial 4G router USES the least time algorithm or the optimal path algorithm to adjust the path of information transmission. If one network path fails or becomes blocked, the industrial 4G router can choose another path to ensure the normal transmission of information. Industrial 4G routers can convert data formats and become necessary devices for network interconnection between different protocols.

 

Industrial 4G routers use path searching protocol to obtain network information, and use path searching algorithm and criterion based on “path searching matrix” to select the optimal path. According to the OSI reference model, an industrial 4G router is a network layer system. Industrial 4G routers are divided into single-protocol industrial 4G router and multi-protocol industrial 4G router.

 

The Internet is made up of a variety of networks, of which industrial 4G routers are a very important part. Intranet to be incorporated into the Internet and serve as Internet service, industrial 4G router is an indispensable component, and the configuration of industrial 4G router is also relatively complex.

 

Industrial Switch:

 

Industrial switch is a device that expands the network and provides more connection ports for the sub-network to connect more computers. With the development of the communications industry and the advancement of the informatization of the national economy, the network exchange market has been rising steadily. It features high cost ratio, high flexibility, relatively simple and easy to implement. Therefore, Ethernet technology has become the most important LAN networking technology, network switch has become the most popular switch. The switch can be recognized based on MAC address, and can complete the function of packaging and forwarding packet network equipment. An industrial switch can “learn” the MAC address and store it in the internal address table, enabling the data frame to go directly from the source address to the destination address by establishing a temporary switching path between the originator of the data frame and the target receiver. If the network utilization is over 40% and the collision rate is over 10%, the industrial switch can help you solve a few problems. Industrial switches with 100Mbps fast Ethernet and 10Mbps Ethernet ports can run in full duplex mode and can establish dedicated 20Mbps to 200Mbps connections.

 

2. Similarities and differences between industrial 4G routers and industrial switches

 

Similarity

 

(1) “exchange” is a word with a wide range of meanings. When it is used to describe the devices in the second layer of data network, it actually refers to a bridging device; When it is used to describe the third layer of the data network, it refers to a routing device. That is, both industrial switches and industrial 4G routers can be used to exchange network devices, but at different levels.

 

(2) Internet access. It’s all about extending the network.

 

Differences

 

(1) The first industrial switch worked at the OSI/RM open architecture’s data link layer (layer 2), while the industrial 4G router was initially designed to work at the OSI model’s network layer. Since the industrial switch works at the OSI layer 2 (data link layer), it works simpler, while the industrial 4G router works at the OSI layer 3 (network layer), which yields more protocol information, and the industrial 4G router makes smarter forwarding decisions.

 

(2) different industrial switches based on different objects for data forwarding use physical address or MAC address to determine the destination address for data forwarding. Industrial 4G routers, on the other hand, use the ID Numbers (i.e. IP addresses) of different networks to determine the addresses for data forwarding. IP addresses are implemented in software that describe the network on which the device is located, and sometimes these third-tier addresses are also known as protocol addresses or network addresses. MAC addresses are typically hardware-owned, assigned by network card manufacturers, and have been solidified into network CARDS, which are generally immutable. IP addresses are usually assigned automatically by the network administrator or the system.

 

(3) traditional industrial switches can only divide the conflict domain and cannot divide the broadcast domain. Industrial 4G routers can segment broadcast domains. A network segment connected by an industrial switch still belongs to the same broadcast domain, and broadcast packets are spread across all network segments connected by an industrial switch, in some cases leading to communications advocacy and security vulnerabilities. Network segments connected to industrial 4G routers are assigned different broadcast domains, and broadcast data does not pass through industrial 4G routers.

 

Although the industrial switch above the third layer has VLAN function and can divide the broadcast domain, the communication between sub-broadcast domains is not possible, and the communication between them still needs the industrial 4G router.

 

(4) industrial 4G routers provide firewall services, which only forward packets of specific addresses, do not transmit packets that do not support routing protocol, and the transmission of target network packets for knowledge, thus preventing broadcast storms.

E-Lins Industrial router applications

Category : 技术相关

Industrial-grade routers as Internet network layer communication equipment application in all walks of life, brought a lot of convenience for our industry. “E-Lins” introduce the application of industrial router scenario analysis.

 

1 The self-service terminal network

 

E-lins industrial router networking facilitates the wireless networking and remote management of self-service terminals. Operations can be self-service equipment such as self-help harvest home, machines, payment terminal layout to any area of the wireless network coverage, such as shopping malls, neighborhood, community, etc., a substantial increase in business volume.

 

2 The smart grid remote video monitoring

 

Remote video monitoring system has been widely used in intelligent monitoring of transmission lines. The system carries out remote real-time video monitoring of transmission lines, towers and transmission substation of transmission lines. The collected real-time video image information can be transmitted to the management center through the link of industrial wireless router. Real-time monitoring of transmission line state, enhance the level of the lean production management.

 

3 Management of public bicycle in traffic areas

 

Public bike rental system includes management center, customer service sites, bike rental sites of three parts. Industrial router applications in the center of the management of communication management system, through the network operators, box rental management system with the background data forwarding, intelligent parking system and settlement system of data transmission, transfer, and the data transmission function with the other application systems.

 

4 Remote audio-video monitoring of driver’s license test

 

In order to effectively prevent accidents, control the source of safety management and regulate the driver’s license examination, the traffic management bureau of the ministry of public security has been successively implemented in various places to strengthen the management guidance of motor vehicle drivers. Cameras are installed on the driver’s license examination vehicles, and connected with the rear platform through 4G industrial router. The subjects of the driver’s test of automobiles are subject to video and audio monitoring. Print 3 randomly captured test photos on the test report card of each subject, and the test video will be kept for more than 1 year.

 

5 WIFI bus

 

WIFI bus is an important part of wisdom city. Routers through 4 g in the car industry, will be on the way of the 3 g / 4 g mobile communication base station emission signal into stable quality of network signals (such as wi-fi signals), micro letter can easily meet car passengers chat, on QQ, local news, download the APP and other mobile Internet lifestyle. Can fully support all the bus company and scheduling, scheduling, statistical analysis and other business needs; Can also support the bus video image transmission of the monitoring system, once the vehicle accident or emergency, video monitoring system can start immediately, will video transmission to the rear of the console for emergency response and scheduling platform center.

 

6 Intelligent express delivery cabinet

 

The intelligent express delivery cabinet connects and interacts with the central management platform via the operator’s 3G/4G wireless network through wireless router to realize remote management and monitoring. And through the VPN and VPDN, realize the security of the data transmission. Send and receive express real-time, liberate the workforce, the center server for data processing and integration, realizing data sharing, in order to ensure real-time and efficient express business. Real time control of the terminal all express ark centralized remote management, operation condition, reduce operating costs, improve service quality.

 

7 Equipment remote monitoring

 

Using 4 g industrial router to establish a system of numerical control machine tool remote fault diagnosis is to CNC machine tool fault diagnosis technology and the INTERNET of wireless communication technology, the combination of establishing monitoring on nc machine tools, its running status data, and in the center of the enterprise local area network and the INTERNET to establish expert diagnosis and analysis of CNC machine running status diagnosis. It can make fault diagnosis is more flexible and convenient, and can effectively improve the diagnostic accuracy and work efficiency, reduce maintenance time.

 

The industrial wireless router has become a magical device in the field of Internet of things M2M due to its fast transmission rate and strong stability.

Classification of 4G industrial routers

Category : 技术相关

There are many types of 4G industrial routers, which can be divided into different categories from different perspectives. Different types of 4G industrial routers can be used in different environments. The following sections classify the 4G industrial routers from different perspectives.

According to the performance

From the perspective of performance, 4G industrial routers can be divided into linear router and non-linear router.

The so-called wire speed router can transmit freely according to the transmission medium bandwidth, basically without discontinuity and delay. The specific calculation method is the same as that of the switch line speed backplane bandwidth. A wire-speed router is a high-end router with very high port bandwidth and data forwarding capability that forwards packets at the media rate.

Non-wire-speed routers are mid – to low-end routers, but some new wire-access routers also have wire-speed capabilities. The performance of router is mainly affected by CPU performance. If the CPU performance is high, the 4G industrial router is more likely to be a high-performing wire-speed router.

Speed is generally not a measure of a router, and data throughput is one of the references used to measure a router’s maximum data throughput. The routers with the capacity of the rear plates of 4G industrial routers greater than 40Gbps are called high-grade routers. The routers with the capacity of the rear plates between 25Gbps and 40Gbps are called midrange routers, while those with the capacity lower than 25Gbps are considered as low-grade routers. This kind of dividing way is not so absolute, specific parameter needs to make distinguishing according to each manufacturer specific parameter.

According to the structure of the points

The 4G industrial router can be divided into modular router and non-modular router according to the structure Angle.

Modular routing generally only provides basic routing function when leaving the factory. Its interface type and partial extension function are configured according to the actual needs of users. Users can choose corresponding modules according to the network type they need to connect. Different modules can also provide different connectivity and management capabilities. For example, the vast majority of modular routers allow users to choose network interfaces, VPNS, firewalls and other functions, most of which are modular routers.

Routers H685/H700/H720/H750/H820/H820Q/H820QO  from E-Lins are all modular router, can meet the requirements from all over the world.

Non-modular routers are mostly low-end routers, which are mostly used in civilian environments. Primarily used to connect small business customers within homes or isps, supporting virtual private network protocols such as SLIP, PPP, PPTP, and IPSec. These protocols to run on each port, such as ADSL will increase home broadband availability, which will increase the burden of accessing routers. In the future, such router ports will run multiple protocols while avoiding the telephone switched network.

According to the function points

The 4G industrial router is divided into general router and special router. The common civilian router is the general router, that is, the router that can normally use the routing function under the general environment, and there is no other special requirement scenario.

The special router optimizes the routing interface, hardware and so on to realize a certain function. For example, the foreign trade special router changes the local IP through the special router, which can also quickly access some foreign trade stations in China, which is more convenient.

According to the interface points

4G industrial routers can support SDH stm-1 interface, SDH stm-4 interface and SDH stm-16 interface. At present, the router supporting SDH stm-64 interface is high-end 4G industrial router. However, other interfaces are relatively weak, among which stm-1 has two types of optical interface and electrical interface. Stm-1 electrical interface is suitable for local situations where the interference signal is weak. The light interface is usually used for stm-4, stm-16 and stm-64.

according to the perspective of the object of use

The 4G industrial routers can be divided into core router (core level), distribution router (enterprise level) and access router (home level) according to the perspective of the object of use.

The core router, which is the router that forwards packets to the host computer in the network (but not between networks), is the key device to realize Interner network interconnection with other levels of routers. Often used by telecom operators or isps. The throughput of core router is larger, and the requirement of speed and reliability is higher. In order to obtain high reliability, the network system generally adopts traditional redundant technology such as hot backup, dual power supply and dual data path, so that the reliability of backbone router is not a problem.

Distributed routers are used to connect multiple logically separate networks because there are many connected objects, the system is relatively simple, and the data traffic is relatively small. In addition to connecting different networks, distribution routers also need to choose smooth and rapid short-cuts to improve the communication speed, reduce the network communication load, save system resources while improving the unimpeded rate, and maximize the benefit of the network system.

The access router is mainly used for network interconnection in the small local area network. It is often used in the case of small area and simple network environment such as home, small enterprise or net bar.