What Is an IoT Gateway and How to Overcome Challenges in IoT Gateway Applications

PublishTime： 2023-09-15 Article Source：usr News

Let's look at what a "gateway" is. Gateway from the literal sense, is the gate of the network, like a high-speed toll station, any data through, need to check.The functionality of this gate is also very diverse. For example, the content forms at both ends of the gate are different, and the gateway is a translator. Or the gateway will block any problematic data from passing through, and the gateway is a filter.

What is IoT gate ways?

IoT gateways is a communication device in the field of Internet of Things. Position in the hierarchical architecture of the Internet of Things system: perception layer terminal equipment-> gateway-> backbone network-> application.

It can provide upstream and downstream connections and the ability to provide edge computing. The south downlink is connected to the sensing layer equipment, and the north uplink is connected to the transmission channel (upper computer, backbone network, remote machine, cloud platform, etc.).

Basic structure of IoT gateways: southbound interface, northbound interface, security management and protocol conversion.

The northbound interface needs to access the Internet, so the usual choices are RJ45 Ethernet port, optical fiber interface, Wi-Fi, 4G, NB-IoT and other cellular network modules.

The southbound interface is used to connect Internet of Things devices. In addition to the BLE, ZigBee, LoRa, Wi-Fi and other wireless technology interfaces just mentioned, it is also commonly used in Industrial Personal Computer. RJ45 Ethernet port, RS232, RS485 and other wired interfaces on the industrial control computer).It should be noted here that the interface type and number of each gateway device are not fixed, because gateway products generally determine several different specifications and models according to application scenarios.

Different types of gateways need to support different types of protocols and the conversion of different number of protocols, so the protocol conversion function of the gateway generally adopts the plug-in software architecture.

The basic requirement of IoT gateways-long-term unattended and stable operation in harsh industrial scenarios.

IoT gateways are different from traditional routers and switches. Traditional routers and switches are in the computer room, with air conditioning on and special staff to maintain them. Ensure the working environment, such as temperature, humidity, air quality, etc.The working environment of IoT gateways is relatively poor. It may work outdoors, under high temperature and pressure, or even in water. The environment is relatively harsh. So the Internet of Things faces many challenges. Such as:

Challenge 1: How to be compatible with various complex communication modes, interfaces, channels and protocols of various local devices? How to work reliably in harsh environments?

Challenge 2: How to make use of the old and protect the existing investment in the construction?

Challenge 3: How to face the security problem of open IP?

Challenge 4: How to achieve efficient deployment, operation and maintenance of the Internet of Things?

Industrial IoT gateways are driven by a number of challenges.

How to overcome the challenge?

Industrial IoT gateways integrates the integration of local multi-transmission communication link mode and the integration of protocol conversion, communication routing, data exchange, security protection and stable operation.It provides industrial standard design, such as: shockproof, waterproof, anti-electromagnetic interference, etc. It also supports a variety of interfaces and protocols, and can convert the data transmitted by the downlink and suitable for the Internet of Things communication protocol packaging into the data (IP data) that can be recognized by the traditional network communication protocol.In this way, IP data can be transmitted on the uplink. Support edge computing, able to respond quickly; It can also provide full-link encryption interconnection to effectively reduce business risks from the perception layer. IoT gateways supports intelligent operation and maintenance: self-service fault handling, remote testing and diagnosis.

How to be compatible with various devices? The object model data is required to abstract the traditional various access devices. What is a physical model?

The physical model is a digital model of physical entities, but it is mainly aimed at the development of applications and the interoperability of devices in the Internet of Things. If this model goes further and integrates all kinds of data of physical entities, it is a faithful mapping of physical entities.At the same time, in the whole life cycle of the physical entity, it will evolve with the entity, accumulate all kinds of information and knowledge, and promote the optimization of the physical entity. Such a model is the digital twin of a physical entity. The device shadow is used to cache the device state.Instead of accessing the device each time, the application can directly obtain the last updated attribute value of the device through the device shadow. When the device is online, the application instruction can be directly obtained; After the device is offline, it can actively pull application instructions when it is online again.

If the device network is stable, many applications request the device status, and the device needs to respond multiple times according to the request, even if the response results are the same. However, it is possible that the processing capacity of the device itself is limited, and in fact, it cannot be loaded with multiple requests.By use that device shadow mechanism, the device only needs to actively synchronize the state to the device shadow once, and a plurality of application program request the device shadow to acquire the device state, so that the latest state of the device can be acquired, and the decoupling of the application program and the device is realize. For example, the switch status of the smart circuit breaker lamp can be controlled remotely or changed locally through a physical switch.If the network is unstable, the state stored on the platform may be inconsistent with the real state of the device, resulting in logical errors in subsequent operations. The device shadow can solve this problem by achieving the consistency of server and device attributes through two-way synchronization.

IoT gateways key features

Management functions. IoT gateways can obtain the attributes and real-time status information of each node, and realize the functions of node status control, wake-up and sleep, online diagnosis, and support the automatic management of nodes through secondary programming.

Source addressing function. Addressing technology can ensure that the information of each node is accurately located and queried in real time to meet the needs of cross-domain communication. Because the node address structure is different from the domain name structure of DNS, new source addressing techniques need to be developed.

Protocol conversion and data format standardization. In order to realize the data exchange between the wireless sensor network and the traditional communication network, the gateway needs to act as the role of protocol conversion, encapsulate the uploaded standard format data uniformly, and unpack the sent data into standard format data, so that the instructions can be recognized.

IoT gateways are typically designed based on industrial computers to meet performance and application requirements, and to manage the resources of the entire system. Due to the limitations of real-time, stability, environment and cost in industrial applications, IoT gateways are often based on the combination of wireless wide area network (WWAN) and local field bus to adapt to various complex industrial environments.At present, the mature wireless Wan communication technologies are GPRS technology, 4G technology and satellite communication technology, and the widely used field bus technologies are CAN, PROFIBUS, LONWORKS, HART, MODBUS and so on.

Data transfer can operate under active or passive working mechanisms.When in an active working mode, data transmission can be generated only when the controlled data is changed or a timing task is set, and the method has the advantages of simplifying the acquisition function of the terminal and reducing the running power consumption; When in a passive working mode, data transmission can be generated only when an actively sent query instruction is received, the authority of the monitoring center is given, but the power consumption is increased,The transmission efficiency is reduced. IoT gateways adopts a hybrid data transmission mechanism, uses a response mechanism to intercept two-way data, and uses an active mechanism to collect transmission data at a fixed time with multiple thresholds, thus taking into account the advantages of active and response, and achieving a balance between power consumption and transmission efficiency.

Does IoT gateways need to support edge computing?

In the era of interconnection of all things, the increase of Internet of Things devices has led to a lot of data need to be transmitted to the cloud for analysis, which also brings a lot of pressure on the cloud and transmission bandwidth, and in the process of transmission, there will be a risk of data leakage.Data is calculated at the edge, which reduces the pressure of cloud processing data and avoids the risk of data leakage. It not only meets the needs of industry digitalization in agile connection, real-time business, data optimization and application intelligence, but also meets the key needs of security and privacy protection.

The Internet of Things collects information from the underlying terminal equipment, accesses the gateway through the Internet of Things communication technology (such as ZigBee, RF, Wi-Fi, RE, RS-485, PLC, etc.), and then accesses the network through the communication technology (3G, 4G, Ethernet, LTE, xDSL, etc.). The information is transmitted to the Internet of Things platform (server), and if a rule strategy is made on the platform, a command is issued directly at the platform.Nding the command to a gateway through a traditional network, finding a corresponding device, sending the command to the device, and executing the command by the device; If there is no rule policy, the application docking platform can be operated on the application side (mobile APP), and the operation command is sent to the platform. In the same principle, the operation command is sent to the Internet of Things terminal device to execute the command.

If the traditional network between the gateway and the platform is not guaranteed, such as congestion and high delay, the data will not be transmitted to the platform, and the real-time of the service will not be guaranteed. So it provides computing power at the gateway, that is, edge computing.

Edge computing is the use of local idle resources to compute on the network edge nodes close to the terminal equipment, providing connectivity, computing, storage, control and application functions. It meets the needs of users for real-time, intelligence, security and data aggregation.

Core value of edge computing?

Support real-time service.

Support edge intelligent analysis and processing.

Data aggregation, private security domains.

Industrial IoT gateways have a wide range of applications. Such as charging pile, power meter reading, street lamp, bus, Internet of Things in the park, etc. It provides low power consumption, intelligent edge computing, real-time business processing and other functions.

Cloud platform system architecture of Internet of thin.

The cloud platform of the Internet of Things mainly includes four components:

Device access:

a secure two-way connection can be established between the smart device and the cloud;

Device management:

services include life cycle, device grouping, device shadow, physical model, data analysis, data storage, online debugging, firmware upgrade, remote configuration, real-time monitoring, etc.;

Rule engine:

The rule engine implements data flow and scenario linkage by creating and configuring rules. Its main function is to filter and forward the data of the Internet of Things platform to other cloud computing products.

Security authentication and authority managemen

1.Realize remote control of industrial field equipment;

2. Realize remote upgrade of equipment firmware, program upload and download, and flexible access to various equipment management platforms;

3. Realize remote control of touch screen and remote mapping of configuration screen in the industrial field;

4. Remote communication with multiple PLCs or touch screens at the same time;

5. Realize the hardware analysis of mainstream protocols such as Siemens, Mitsubishi, Omron, Schneider, Delta, Huichuan, Hollysys, Panasonic, Yonghong, Haiwei and MODBUS series PLC;

6. Realize PLC remote monitoring, PLC remote programming, PLC remote debugging, PLC remote uploading and downloading, PLCremote control, PLC data acquisition, and PLC remote communication;

At present, there are many kinds of equipment access hardware in the market, such as data acquisition gateway, industrial AP, industrial DTU, industrial gateway, edge computing box and industrial router.

Internet of things data acquisition gateway, also known as industrial Internet of things intelligent gateway, wireless data acquisition gateway, communication acquisition gateway, wireless gateway, industrial communication gateway, industrial Ethernet serial port intelligent gateway, RS485 serial port Modbus intelligent gateway belongs to wireless sensor network products.It has the characteristics of high integration, integrates data reception, protocol conversion, wireless communication transmission and other functions, supports multiple communication protocols and communication modes, and can adopt 4G, 5G, wifi, Ethernet and other communication modes.

1. Industrial AP

Based on various wireless connections (WIFI, Bluetooth, LoRa), realize the connection with equipment and internal matrix networking, and realize data transmission through the upper connection equipment (gateway, industrial personal computer).

2. Industrial DTU data transparent transmission gateway and data transmission unit

Based on various wireless connections (WIFI, Bluetooth, LoRa, etc.), realize the transparent transmission of single device data, and transmit the data on the device to the upper computer (local monitoring system, host) or cloud (telecontrol station, Internet of Things cloud platform, device management cloud platform) by means of serial port to Ethernet. It is resolved by the host computer or cloud according to the data protocol agreed by the equipment.

3. Industrial Gateway

In addition to device connection and network transmission, the gateway has a built-in protocol stack, which can realize the conversion between protocols, run the linkage script locally to control the device, set the data transmission strategy and logic judgment, and install the operating system as an intelligent machine with the corresponding external/local configuration interface.

4. Edge computing IoT gateways

In addition to the various functions of the traditional industrial gateway (multi-device connection, data acquisition, protocol conversion, script execution, etc.), as the upper computer, it can receive data from the lower devices such as industrial AP/industrial DTU/gateway, store data through the storage space of the device itself, select application data and upload it to the cloud.And use the device's own chip to perform local operations and execution of some scripts and APP requirements.

At the same time, as an edge computing node rooted in the production site, it has the characteristics of lightweight, high performance, low power consumption and convenient access. It can process and analyze massive equipment data locally, improve computing efficiency, and also serve as the carrier of industrial interconnection and industrial APP to shorten the response time of various business operations on the industrial Internet platform.Good value for money.

5. Industrial Router

Realize different wireless modes (WIFI) in the enterprise workshop. Bluetooth. Ethernet) access devices and transmit data to cloud servers through 4G/5G networks.

Generally speaking, industrial AP and industrial DTU are almost the same. I upload whatever you give me, but if I can't get on the Internet, industrial DTU can also help me bring the data up.

The industrial gateway can store some data, upload some useful data, and control the equipment by the way.

Edge computing gateways, as the name implies, can compute and run programs, bringing only the data they need with them.

Industrial routers are data transmission, which can ensure the connection of equipment in the workshop field environment and try their best to transmit data.

In addition to the common device access hardware described above, there are PLC Internet of Things modules and industrial computers.

6. PLC Internet of Things module

It is responsible for uploading the data of PLC, uploading the data of PLC body and other modules to the host computer or cloud through the Internet of Things module by means of various wireless transmission modes, and controlling the equipment by means of PLC.

7. Industrial control computer

It is an alternative version of the edge computing box, which can be used with an external display. Its basic functions and network transmission mode are the same as those of the edge computing box. It also has the functions of data reception/data storage/data upload, local computing and execution of corresponding programs. Some industrial personal computers are all-in-one machines with touch screens, which are more powerful in function.It can do everything that gateways and edge computing boxes can do.

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