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Basic Knowledge Of Industrial Ethernet Networking Equipment Apr 14, 2017

Today's control system and factory automation system, the application of Ethernet is almost as popular as PLC. But the knowledge of the field engineers to Ethernet is mostly from their knowledge of traditional commercial Ethernet. Many control systems engineering implementations are even directed directly to technicians from the IT department. However, it engineers understand Ethernet, often limited to the implementation of office automation Business Ethernet experience, the simplification and commercialization of industrial Ethernet in industrial control system can not really understand the significance of industrial Ethernet in the industrial field, and the special functions inherent in industrial Ethernet can not be used, which often result in the incomplete implementation of industrial Ethernet site, leaving unstable factors to the whole control system.

What are the factors to consider in choosing the right industrial Ethernet? In simple terms, it is to be considered from Ethernet communication protocol, power supply, communication rate, industrial environment certification, installation mode, Shell's influence on heat dissipation, simple communication function and communication management function, electric port or light mouth. These are the most basic needs to understand the product selection factor. If you have higher requirements for network management of Industrial Ethernet, you need to consider the advanced features of the selected product, such as: signal strength, port settings, error alerting, serial port use, backbone (TrunkingTM) redundancy, loop network redundancy, Quality of Service (QoS), Virtual LAN (VLAN), Simple Network Management Protocol (SNMP), port mirroring, and so on other industrial Ethernet management switches can be provided. Different control systems have different requirements for the management functions of the network, and naturally have different requirements for the use of management switches. Control engineers should choose the industrial Ethernet products suitable for their systems according to the design requirements of their systems.

Because of the high demand of industrial environment for the reliable performance of industrial control network, redundant functions of industrial Ethernet emerged. From rapid spanning Tree redundancy (RSTP), Ring-Network redundancy (RapidRingTM) to trunk redundancy (TrunkingTM), there are different advantages and characteristics, and control engineers can choose according to their own requirements. In order to better help you understand and learn the characteristics of industrial Ethernet redundancy technology, let us first review the following Ethernet equipment development process.

Hub (Hub)

I believe most people are familiar with hubs. Many people use this simple device to connect a variety of Ethernet-based devices such as PCs, programmable controllers, and so on. The hub receives a message from one port and broadcasts the message to all other ports. For each message from either port, the hub passes it to the other ports. In the aspect of messaging, hubs are low-speed and inefficient, and there may be a message conflict. However, the use of hubs is very simple-actually plug and play. Hubs do not have any flashy features or redundancy.

Non-managed switches (Unmanaged switch)

The development of hubs produces a device called a non-managed switch. It implements the routing function of messages from one port to another, and is more intelligent than the hub. Non-managed switches automatically detect network speeds for each network device. In addition, it has a function called "MAC Address Table" to identify and memorize devices in the network. In other words, if Port 2 receives a message with a specific identifier, then the switch sends all messages that have that particular identification code to port 2. This intelligence avoids the message conflict, improves the transmission performance, and the relative hub is a great improvement. However, non-managed switches do not implement any form of communication detection and redundant configuration.

Managed switches (Managed switch)

Ethernet connectivity devices The next generation of products are managed switches. With a relative hub and unmanaged switches, managed switches have more complex features, and a lot of prices are higher — usually 3-4 times as a non-managed switch. Managed switches provide more functionality, and can typically be fully configured through a network-based interface. It can automatically interact with network devices, and users can manually configure the speed and flow control of each port. Some older devices may not be able to use automatic interactivity, so manual configuration features are indispensable.

Most managed switches also provide advanced features, such as SNMP (Simple Network Management Protocol) for remote monitoring and configuration, port mappings for diagnostics, and VLAN (virtual LAN) for network devices to be used to ensure prioritization of priority messages through the ranking of the priorities. With management switches, redundant networks can be formed. With a circular topology, a managed switch can form a circular network. Each managed switch can automatically determine the optimal transmission path and alternate path, and automatically block (block) alternate paths when the priority path breaks.