At the beginning of the design of ordinary Ethernet, the application needs of industrial networks were not considered. Therefore, when network equipment is deployed in industrial sites, faced with harsh working environments, severe electromagnetic interference, etc., the stability of ordinary commercial switches will suffer. Great challenge. In this regard, industrial switches with high reliability, stability and security have emerged, becoming a transmission tool that can adapt to complex industrial environments and facilitate the deployment of industrial automation networks.
What is an industrial switch?
Industrial switches are also called industrial Ethernet switches. Due to the network standards used, their openness, wide application, low price, and transparent and unified TCP/IP protocol, Ethernet has become the main communication standard in the field of industrial control. .
The difference between industrial switches and ordinary switches
Industrial switches are different from civilian and commercial switches. They are not essentially different from other switches in terms of network layer, data link layer, protocol, etc. However, due to their special working environment and functional requirements, industrial switches have many civilian and commercial switches. It solves technical problems such as real-time communication, network security, intrinsic safety and safe explosion-proof technology, and adopts some measures suitable for industrial environments, such as waterproofing and anti-vibration.
Compared with ordinary switches, industrial switches mainly have two differences in functions and performance:
Functionally
Industrial Ethernet switches are closer to industrial network communications in terms of functionality, such as interconnection with various field buses, equipment redundancy, and real-time equipment, etc.;
Performance
Mainly reflected in adapting to differences in external environmental parameters. In addition to many particularly harsh environments such as coal mines and ships, industrial environments also have environments with special requirements in terms of EMI (electromagnetic compatibility), temperature, humidity, and dust prevention. Among them, temperature has the widest impact on industrial network equipment.
Industrial switch features
Due to differences and requirements in functions and performance, industrial switches have the following main features compared with ordinary switches:
Components
Industrial Ethernet switches have very high requirements for the selection of components. To better adapt to the needs of industrial production sites, components need to have anti-static, lightning protection, ultra-high and low-temperature resistance, and other requirements.
Mechanical environment
Industrial Ethernet switches can better adapt to harsh mechanical environments, including resistance to vibration, impact, corrosion, dustproof, waterproof, etc.
Climate environment
Industrial Ethernet switches can better adapt to poor climate environments, including temperature, humidity, etc., and can be used normally in ambient temperatures of -45°C to +75°C, with relative humidity of 5% to 95% without condensation.
Electromagnetic environment
Industrial Ethernet switches have strong anti-electromagnetic interference capabilities, and the electromagnetic interference protection level reaches level 4.
Operating Voltage
Industrial Ethernet switches have a wide operating voltage range, supporting DC 12/24V, and AC/DC 85~265V wide voltage options. Ordinary switches have higher voltage requirements and mostly provide fixed voltage power supply.
Power supply design
Ordinary switches have a single power supply, while industrial Ethernet switches have dual power supplies to back up each other. In addition, they also have a power loss alarm function.
Installation method
Industrial Ethernet switches can be installed in DIN rails, racks, etc. Ordinary switches can be installed in general racks or desktops.
Heat dissipation method
Industrial Ethernet switches use fanless casings for heat dissipation to reduce the impact of dust and prevent equipment failures caused by fan failures, while ordinary switches use fans for heat dissipation.
When choosing industrial switches
Industrial sites must choose appropriate industrial Ethernet switches instead of cheap commercial switches. The necessity of selecting industrial switches in industrial sites can be determined from the following aspects.
Certainty
Since the MAC layer protocol of Ethernet is CSMA/CD, this protocol causes conflicts on the network, especially when the network load is too heavy, it becomes more obvious. For an industrial network, if there are a large number of conflicts, data must be retransmitted multiple times, which greatly increases the uncertainty of inter-network communication. This uncertainty from one place to another in the industrial control network will inevitably lead to a reduction in system control performance.
Real-time
In industrial control systems, real-time can be defined as the measurability of the system’s response time to an event. That is, after an event occurs, the system must respond within an accurately foreseeable time frame. However, the industry has very strict real-time requirements for data transmission, and data updates are often completed within tens of ms. Also due to the CSMA/CD mechanism in Ethernet, when a conflict occurs, the data must be retransmitted, and it can be tried up to 16 times. This conflict resolution mechanism comes at the cost of time. And once a disconnection occurs, even for just a few seconds, it may cause the entire production to stop or even cause equipment and personal safety accidents.
Reliability
Since Ethernet was originally designed, it was not based on industrial network applications. When it is applied to industrial sites, it faces harsh working conditions, severe interference between lines, etc., which will inevitably cause its reliability to decrease. In a production environment, industrial networks must have good reliability, recoverability, and maintainability. That is to ensure that when any component in a network system fails, it will not cause the application, operating system, or even the network system to collapse and paralyze.
Application areas
Industrial switches are generally used in industrial production situations. They usually have various appearances and installation forms. Depending on the application, they are required to be waterproof, dustproof, earthquake-resistant, and anti-electromagnetic interference. Of course, the reliability requirements are also very high, and they also need to operate 24 hours a day without interruption for a long time. Some automatic control applications require low forwarding delay, and some require redundant power supplies, DC 24V power supplies, etc. Industrial switches are designed with the complex conditions of the industrial site in mind so that they can better adapt to the industrial environment and play the role of the switch.
The industrial switch market is mainly used in the fields of power automation, factory automation, coal mine automation, rail transportation, wind energy, and wind power, followed by metallurgy, petroleum and petrochemicals, road traffic control automation, building automatic control systems, oil field control automation, hydropower station control automation, and computer room monitoring. systems, water conservancy monitoring, environmental monitoring, and other industrial control automatic places.
Industrial switches are used in some industrial sites with harsh environmental conditions due to their high protection level (generally IP40), strong electromagnetic compatibility (EMS level 4), and stable working performance, providing strong protection for industrial communications.