The Internet of Things is growing rapidly and moving towards the Internet of Everything (IoE). In the era of full connectivity, the surge in the number of device connections and the amount of data in the Internet of Things has promoted the development of edge computing technology. Edge computing Internet of Things innovatively brings edge computing architecture into the field of Internet of Things, providing data processing, storage and application near the edge of things.It solves the "last mile" problem of Internet of Things communication and realizes the intelligent connection and efficient management of Internet of Things devices.
Let's introduce Edge Computing Gateway from four aspects.
1. Why do we need Edge Computing Gateway?
2. What is the purpose of the edge computing gateway?
3. Main features of edge computing gateway
4. Typical application of edge computing gateway
Nowadays, the Internet of Things has become a key force to promote a new round of global scientific and technological revolution and industrial transformation.
What is the Internet of Things? Simply put, the Internet of Things makes the Internet of Things, and its ultimate goal is to connect everything.
With the rapid development of Internet of Things technology, all walks of life begin to transform digitally, connecting more and more devices to the Internet. Statistical authorities predict that by 2025, the number of global Internet of Things device connections will reach 100 billion. Under this trend, enterprises will face the following challenges:
When massive data is migrated to the cloud for processing, the lack of real-time data analysis and processing capabilities greatly increases the burden of data processing in the cloud.
It is difficult to centrally deploy and manage numerous IoT devices and applications, as well as diverse interfaces and protocols.
Edge Computing Internet of Things: The Combination of Edge Computing and Internet of Things
Edge computing greatly simplifies the processing of massive terminal data in the cloud.
Edge computing is deployed at the edge of the network near things or data sources, and provides edge intelligent services through an open platform that integrates network, computing, storage and application capabilities. The data collected by the terminal device is directly analyzed and processed in real time at the edge of the network without uploading to the cloud.Edge computing meets the key requirements of industry digitization for agile connectivity and real-time data optimization.
The combination of edge computing and Internet of Things technology has given birth to the edge computing Internet of Things. Edge computing Internet of Things brings edge computing architecture into the field of Internet of Things. Edge Computing Gateway, which integrates network, computing, storage and application capabilities, can be deployed at the edge of the network near the device or data source to provide device management and control services at the edge of the network.Therefore, the edge computing Internet of Things solves the "last mile" problem of industrial Internet of Things communication, and realizes the intelligent connection and efficient management of Internet of Things devices.
The Internet of Things for Edge Computing aims to meet the following requirements:
Adapt to a variety of physical interfaces and protocols, so that the Internet of Things terminal can access the Internet quickly and smoothly.
Realize the unified management of a large number of terminal devices.
Realize local processing of local traffic and rapid response.
Open the industry collaboration system.
The following figure shows the edge computing IoT architecture, which is characterized by edge intelligence and cloud management. Through the gateway's open edge computing capability, the edge computing Internet of Things quickly adapts to the intelligent data processing needs of all walks of life, and realizes the quick response of millisecond level key businesses, local aggregation and optimization of data, and active return of high-value data to the cloud.
Edge Computing Internet of Things Architecture
The Edge Computing IoT architecture uses two core components: the Edge Computing Gateway and the cloud-based IoT platform.
Edge Computing Gateway is an Internet of Things gateway with edge computing capability, which can analyze and process massive terminal data locally.
Support rich industrial Internet of Things interfaces (such as PLC, RF, RS-485, DI) and protocols, and flexibly access various sensors and terminals.
Open hardware and software resources to support container deployment. Industry applications can be deployed in containers on demand to achieve local processing of access terminal equipment data.
Cloud-based Internet of Things platform can be interconnected with various industry application systems to achieve intelligent connection of terminal devices:
Cloud management architecture is adopted to centrally manage a large number of terminal devices and reduce operation and maintenance costs.
It adopts open architecture and open standard northbound application programming interface (API) to interconnect with third-party industry application systems.
The cloud platform is open
In the edge computing Internet of Things solution, the cloud-based Internet of Things platform uses cloud computing technology to achieve unified management of networks, devices, containers and applications in the cloud. The platform also provides an open northbound API to support flexible docking with third-party industry application systems, as shown in the figure below.
Open architecture
Cloud Internet of Things platform adopts open software architecture, provides standard RESTful northbound API, interconnects with application systems in various industries, and realizes application value-added services.
Service integration
The cloud-based IoT platform manages gateways, containers, and applications in a unified way, and supports the installation of containers and applications.
Cloud-based deployment
The cloud-based IoT platform supports distributed cluster deployment, seamless capacity expansion, and centralized management of a large number of IoT gateways.
Open Gateway of Cloud-Based Internet of Things Platform
Gateway open
As shown in the figure below, Edge Computing Gateway supports container deployment, allowing users to install their own business applications in the container. In addition, it provides various eSDK interfaces for containers and application invocation resources.
Container is a lightweight, Linux-based approach to virtualization isolation. A traditional virtual machine consists of CPU, memory, disks, and peripherals and is used as a real machine. In contrast, Linux containers implement resource isolation and allocation based on the Linux kernel, making the applications in them think they are running on separate machines.
Edge computing Internet of Things has been widely used in power distribution, smart city, smart integrated energy services (IES) and other fields. It has become an important driving force for cross-industry digital transformation. The following describes the application of edge computing Internet of Things in power distribution and intelligent IES scenarios.
Internet of things for power distribution
The Internet of Things combines traditional distribution automation technology with Internet of Things technology to realize the digital transformation of distribution network. This solves many long-standing problems that traditional industrial control technology can not solve, such as the management of many terminal devices and business management and control.Therefore, the Internet of Things for power distribution can provide better user service experience and improve the efficiency of service operation.
In the power distribution Internet of Things scenario, the edge computing Internet of Things adopts the "cloud-tube-edge-end" architecture to achieve full connection and intelligent management.
Cloud: refers to the cloud master station. It consists of a next-generation distribution automation master station, a micro-application management and control center, and Agile Controller-IoT. These components work together to provide a variety of services and capabilities, including distribution terminal unit (DTU) management, online equipment monitoring, outage repair, asset management, big data analytics, and artificial intelligence (AI) applications.
Conduit: The communication network that enables data exchange between the cloud and the edge. WAN communication networks include Ethernet and wireless networks. The local communication network mainly uses PLC-IoT, RF-Mesh and other communication technologies to transmit data between the terminal equipment and the edge.
Edge: Edge Computing Gateway is deployed at the edge of the network to provide a container platform that allows users to install business applications in containers to meet business needs. In addition, the Edge Computing Gateway provides an open API in the container for application calls.
Equipment: LV power distribution equipment adopts intelligent core communication module to realize communication between intelligent terminal equipment and Edge Computing Gateway. Huawei provides intelligent core communication modules and open APIs for third-party manufacturers to carry out secondary integration of low-voltage equipment.
RS485 serial bus is widely used in the communication distance from tens of meters to several kilometers. RS485 uses balanced transmission and differential reception, so it has the ability to reject common mode interference. Coupled with the high sensitivity of the bus transceiver, which can detect voltages as low as 200 mV, the transmitted signal can be recovered from kilometers away.
RS485 adopts half-duplex working mode, and only one point can be in the transmitting state at any time, so the transmitting circuit must be controlled by the enable signal. RS485 signal to Ethernet signal, that is, RS485 Ethernet converter equipment, has its role in industrial, security, remote meter reading and other scenarios, using its signal conversion function to achieve signal conversion and improve the network.
RS485 to Ethernet provides the function of converting serial port to network, which can convert RS485 serial port to TCP/IP network interface and realize bidirectional and transparent data transmission between RS485 serial port and TCP/IP network interface. The serial device can immediately have the function of TCP/IP network interface, connect the network for data communication, and expand the communication distance of the serial device.
RS485 is a differential signal negative logic, + 2V ~ + 6V represents "1", and -2V ~ -6V represents "0". RS485 communication interface is divided into two types, one is two-wire system, and the other is four-wire system. The two-wire system is a half-duplex communication mode, and the four-wire system is a full-duplex communication mode. RS485 communication interface, strong anti-interference ability, good anti-noise interference.In industrial control, RS485 bus is widely used because of its simple interface, convenient networking, long transmission distance and other characteristics.
The RS485 interface is a half-duplex data communication mode. The half-duplex network composed of the interface is generally a two-wire system in use, and the shielded twisted pair is often used for transmission. Such a wiring mode is a bus-type topology, and 32 nodes can be connected to the same bus at most. RS485 in the communication network uses a master with multiple slaves.In most cases, a simple pair of twisted pairs is used to connect the two ends of the "A" "B" "of each interface when connecting RS485 communication. The RS485 interface connector adopts the 9-core socket head of DB-9, the RS485 interface of the intelligent terminal adopts DB-9, and the keyboard interface RS4485 connected with the keyboard adopts DB-9.
"Advantages."
The wiring is simple: only 2 wires are needed, and the shielded wire interface of the network cable is adopted;
Long communication distance: differential mode communication is adopted, and the communication distance is long;
Multi-machine networking: RS485 supports mounting multiple terminals on line, and realizes multi-machine communication by means of query-response;
"Solution."
RS485 to Ethernet hardware converter is divided into two types: RS485 Ethernet converter and serial networking module.
The RS485 Ethernet converter realizes the conversion of the RS485 interface into the TCP/IP interface, and with the use of the virtual serial port driver on the computer side, the TCP/IP connection is virtually converted into a serial port again.
The virtual serial port driver creates virtual serial port numbers such as COM5 and COM6 in the driver layer of the computer, and binds the remote RS485 Ethernet converter with the virtual serial port to realize communication.
After using the hardware and software system of the solution, the Rs485 device is equivalent to the expansion of the network, and the original hardware and software programs do not need to be modified.
Basic functions: RS485 serial port to Ethernet, bidirectional transparent transmission, support Modbus forwarding;
Guide rail installation: exquisite volume, standard 35mm guide rail installation, easy layout and installation, convenient for later maintenance;
Operating mode:
TCP Server: As a Server, the device can be set with two TCP clients to perform transparent data transmission with the device at the same time, so as to solve the problem of simultaneous communication between multiple clients and the device. It can also be used as a standby network channel for switching communication;
TCP Client: As a Client, the device can be set to face four server addresses at the same time, actively initiate connections to the server, and as a Client, support the setting of custom heartbeat packets and handshake packets;
UDP Server: as the Server end, the device supports multiple UDP clients to transmit data with the device;
UDP Client: as the Client end, the device actively communicates with the UDP Server and transparently transmits data with the RS232 serial port;
UDP multicast: as the Client end, the device can realize the mutual communication between the devices in the multicast;
Http server: as the HTTP server, the device supports HTTP communication in the local area network through HTTP (get);
What are the features of the RS485 repeater
RS485 is convenient for multipoint interconnects, eliminating many signal lines. Using RS-485, a distributed system can be networked, allowing up to 32 drivers and 32 receivers to be connected in parallel. In view of the shortcomings of RS-232-C, the new standard RS-485 has the following characteristics:
(1) Electrical characteristics of RS-485: logic "1" is represented by the voltage difference between two lines + 2 V ~ + 6 V, and logic "0" is represented by the voltage difference between two lines -6 V ~ -2 V. 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 the TTL level, so it is convenient to connect with the TTL circuit.
(2) Maximum data transmission rate: 10Mbps
(3) RS485 interface adopts the combination of balanced driver and differential receiver, which has strong anti-common-mode interference ability, that is, good anti-noise performance.
(4) The standard maximum transmission distance of RS-485 interface is 4000 feet, but in fact it can reach 3000 meters.
(5) The RS232-C interface allows only one transceiver to be connected on the bus, that is, single-station capability; The RS-485 interface only allows up to 128 transceivers to be connected on the bus, that is, it has multi-station capability, so users can easily establish a network of devices using a single RS-485 interface.
RS485 repeater, as RS485/422 data relay communication product, features and functions:
High efficiency: The 485 repeater adopts a professional I/O circuit and uses the automatic control technology of data flow direction to automatically distinguish and control the direction of data transmission. It can easily switch between the RS-485 bus and the RS-422 bus without changing the software and hardware. Zero delay design is adopted, and the transmission speed is fast. Automatic detection of serial port signal rate, no need to set the serial port baud rate.
Anti-interference: 485 bus requires 485 equipment to be as close as possible to the bus backbone. Using 485 bus repeater, the bus topology can be changed into "T" topology, which is convenient for field construction. If the 485 transmission line reaches a certain distance and is in a complex external environment, it is vulnerable to external interference such as electromagnetic induction of the external environment.
Stability: The lightning protection tube in the 485 repeater can effectively suppress lightning and ESD, and provide lightning surge protection power of 600 W per line. Absorb external interference such as electromagnetic induction of the external environment, thereby protecting the stability of the 485 bus.
Expansibility: Due to the extension of 485 bus transmission distance or the increase of devices in 485 bus, 485 signals will be continuously attenuated, which may lead to 485 bus instability or even unavailability. 485 bus repeater can enhance and amplify the existing 485 signals. Increase the number of 485 devices in an RS-422/RS-485 bus network.
Isolation: In the field construction, due to the long distance of the 485 bus, the potential difference is formed, resulting in common mode interference, resulting in reduced stability. Photoelectric isolator can provide isolation voltage, effectively isolate and prevent common-ground interference. The DC/DC module can completely isolate the power supply at both ends.
RS232 interface standard. RS-232 interface conforms to the serial data communication interface standard formulated by the Electronic Industry Alliance (EIA) of the United States. It is widely used in the connection of computer serial interface peripherals. For example, some old PCs are equipped with RS232 interface. RS-232 is one of the mainstream serial communication interfaces. RS is the abbreviation of English "Recommended Standard", 232 is the identification number, and C represents the number of revisions.
The RS-232-C bus standard has 25 signal lines, including a main channel and an auxiliary channel. In most cases, the main channel is mainly used. For general duplex communication, only a few signal lines are needed, such as a transmit line, a receive line, and a ground line.Another reason for the short transmission distance is that RS-232 is a single-ended signal transmission, which has problems such as common-ground noise and inability to suppress common-mode interference, so it is generally used for communication within 20 m.
Due to the early appearance of RS232 interface standard, it is inevitable that there are shortcomings. The RS-232-C standard specifies data transmission rates of 50, 75, 100, 150, 300, 600, 1200, 2400, 4800, 9600, 19200 baud per second.In a device network composed of RS232 or RS485 devices, if the number of devices exceeds two, RS485 must be used as a communication medium, and the devices in the RS485 network can communicate with each other only through the transfer of a Master device, which is usually a PC, and only one Master device is allowed to exist in the device network. The rest are all Slave devices.Fieldbus technology is based on ISO/OSI model and has a complete software support system, which can solve the problems of bus control, conflict detection, link maintenance and so on.
"Field of application."
RS485 is often used in long-distance transmission with high data transmission rate, and the commonly used equipment includes point-of-sale terminals (POS), measuring instruments and large special automation machines. The commonly used RS-232 is now generally used in short-distance transmission with low data transmission rate, and can work effectively in noisy environments, such as factories, public sites and so on.Its common equipment includes low-speed modems, industrial control equipment, programmable logic controllers (PLC), computer numerical control (CNC) machine tools, robots, embedded control computers, medical instruments and equipment, and embedded controller development systems.
However, in normal applications, we often need to convert between two different interface types. At this time, we can use the popular USB interface, which can help us convert to RS-232 interface and RS-485 interface.
To sum up, RS232 is suitable for short-distance and low-rate transmission, while RS-485 is suitable for long-distance communication transmission. RS-485 is a new interface standard to overcome the shortcomings of RS-232 interface. Because of its good anti-noise interference ability and multi-station ability, it has become the preferred standard.
In the conventional 485 bus communication, the 485 repeater, 485 converter and other equipment will encounter many problems in the application process, such as: unable to communicate, abnormal data upload and download, communication interference, abnormal flickering of communication indicator light, communication instructions on and off, which affect the normal use. The usual detection method is as follows:
1. Common ground method: use one wire or shielded wire to connect the grounding points of all 485 equipment to avoid potential difference affecting communication between all equipment.
2. Termination resistance method: Connect a termination resistance of 120 ohms in parallel on 485 + and 485- of the last 485 device to improve the communication quality.
3. Middle section disconnection method: check whether the equipment is overloaded, the communication distance is too long, and the damage of a certain equipment has an impact on the entire communication line by disconnecting from the middle;
4. Separate wire pulling method: simply and temporarily pull a wire to the equipment to rule out whether the communication failure is caused by wiring.
5. Converter replacement method: Replace several converters to rule out whether the converter quality problem affects the communication quality.
6. Notebook debugging method: First ensure that the notebook computer is a device with normal communication, and then replace it with another computer for communication. If it is possible, it indicates that the serial port of the computer may be damaged or injured.
