Industrial Ethernet composition - Solutions - Huaqiang Electronic Network

Today, industrial Ethernet applications are widely used. Today's control systems and factory automation systems often use industrial Ethernet technology to complete industrial control tasks. However, IT engineers' understanding of industrial Ethernet is often limited to office automation commercial industrial Ethernet. This may lead to the simplification and commercialization of industrial Ethernet in the control system system. It can't really understand the meaning of industrial Ethernet in the industrial field, and can't really take advantage of the special functions inherent in industrial Ethernet, often causing industrial Ethernet. Incomplete implementation of the site left instability in the entire control system.

What factors should be considered when choosing the right industrial Ethernet? Simply speaking, it should consider the industrial Ethernet communication protocol, power supply, communication rate, industrial environment certification, installation method, the impact of the enclosure on heat dissipation, simple communication functions and communication management functions, electrical ports or optical ports. These are the product selection factors that are most basic to understand. If you have higher requirements for industrial Ethernet network management, you need to consider the advanced features of the selected products such as: signal strength, port settings, error alarms, serial port usage, trunkingTM redundancy, ring redundancy, services Quality (QoS), Virtual Local Area Network (VLAN), Simple Network Management Protocol (SNMP), port mirroring, and more are available in other Industrial Ethernet management switches. Different control systems have different requirements for the management functions of the network, and naturally there are different requirements for the use of managed switches. Control engineers should select the Industrial Ethernet products that are suitable for their system based on the design requirements of their systems.

Due to the high requirements of the industrial environment for the reliability of industrial control networks, the redundant functions of Industrial Ethernet have emerged. From Rapid Spanning Tree Redundancy (RSTP), Ring Redundancy (RapidRingTM) to TrunkingTM, each has its own advantages and characteristics, and control engineers can choose according to their own requirements.

Industrial Ethernet equipment includes the following important parts.

Industrial Ethernet hub

I believe most people are familiar with hubs. Many people use this simple device to connect various Ethernet-based devices, such as personal computers, programmable controllers, and so on. The hub receives a message from a port and broadcasts the message to all other ports. For each message from any port, the hub will pass it to each of the other ports. In terms of messaging, hubs are slow and inefficient, and message conflicts can occur. However, the use of a hub is very simple - it can actually be plug and play. The hub does not have any flashy features and no redundancy.

Industrial Ethernet unmanaged switch

The development of hubs has resulted in a device called an unmanaged switch. It enables routing of messages from one port to another, making them more intelligent than hubs. Unmanaged switches automatically detect the network speed of each network device. In addition, it has a function called "MAC Address Table" that identifies and remembers devices on the network. In other words, if port 2 receives a message with a specific identification code, then the switch will send all messages with that particular identification code to port 2. This intelligence avoids message collisions and improves transmission performance, a huge improvement over hubs. However, unmanaged switches cannot implement any form of communication detection and redundancy configuration.

Industrial Ethernet Managed Switch

The next generation of industrial Ethernet connectivity devices is the managed switch. Managed switches have more and more complex functions than hubs and unmanaged switches, and are much more expensive—typically three to four times as large as an unmanaged switch. Managed switches provide more functionality and are typically fully configured through a network-based interface. It can automatically interact with network devices, and users can manually configure network speed and flow control for each port. Some old devices may not be able to use the automatic interaction feature, so manual configuration is indispensable.

Most managed switches also typically provide advanced features such as SNMP for remote monitoring and configuration (Simple Network Management Protocol), port mapping for diagnostics, VLANs for network device grouping (Virtual Local Area Network), The priority ranking function for ensuring the passage of priority messages, and so on. With a managed switch, you can set up a redundant network. With a ring topology, managed switches can form a ring network. Each managed switch can automatically determine the optimal transmission path and the alternate path, and automatically block the alternate path when the priority path is interrupted.

Industrial Ethernet Managed Redundant Switch

Advanced managed redundant switches offer special features, especially for redundant systems with strict stability and security requirements. The main ways to build a redundant network are as follows: STP, RSTP; ring network redundancy RapidRingTM and trunking.

1 Industrial Ethernet STP and RSTP

STP (Spanning Tree Protocol, IEEE 802.1D) is a link layer protocol that provides path redundancy and prevents network loops from occurring. It forces the alternate data path to be blocked. If a path fails, the topology can be reconfigured and link reconfigured by activating the alternate path. The network interrupt recovery time is between 30-60s. RSTP (Rapid Spanning Tree Algorithm, IEEE 802.1w) is an STP upgrade that reduces network interrupt recovery time to 1-2s. The spanning tree algorithm has a flexible network structure, but it also has the disadvantage of slow recovery.

2 Industrial Ethernet ring redundancy

In order to meet the real-time characteristics of the industrial control network, RapidRing was born. This is a technique that uses ring networks to provide high speed redundancy in industrial Ethernet networks. This technology allows the network to recover itself within 300ms of the interruption. The faulty relay connection, status indicator and SNMP settings of the IE switch can be used to remind the user of the network disconnection. These can help diagnose where the ring is broken.

RapidRingTM also supports two ring networks that are connected together to make the network topology more flexible. The two rings are connected by two channels, which can be redundant to avoid problems caused by single cable errors.

3 Industrial Ethernet backbone redundancy

By setting up multiple ports of different switches as trunking trunk ports and establishing connections, a high-speed backbone link can be formed between these IE switches. Not only has it doubled the network bandwidth of the backbone link, it has enhanced network throughput, but it also provides another feature, redundancy. If the backbone link in the network has problems such as disconnection, the data in the network will be transmitted through the remaining links to ensure normal network communication. The trunking backbone network adopts a bus type and a star network structure, and the theoretical communication distance can be extended indefinitely. This technology uses a hardware detection and data balance method, so the network interrupt recovery time has reached a new height, the general recovery time is below 10ms.