In the past, one of the main challenges for Ethernet to enter the fieldbus system was its inherent unpredictability. This stemmed from the use of the CSMA/CD (Carrier Sense Multiple Access with Collision Detection) protocol at the data link layer. While this protocol works efficiently under light network loads, it becomes less reliable when the network is heavily congested. In such cases, Ethernet devices would wait for a random time before retransmitting, which introduced delays and compromised the real-time performance of the system. For industrial control networks, where timely communication is critical, this delay was unacceptable. Additionally, traditional Ethernet components—such as connectors, hubs, switches, and cables—were designed for office environments, not the harsh conditions found in industrial settings. These limitations included poor resistance to electromagnetic interference, lack of intrinsic safety features, and an inability to provide power to field instruments.
However, technological advancements have significantly improved Ethernet's suitability for industrial applications. The rise of 100M Ethernet as the industry standard, along with the deployment of 10 Gigabit Ethernet, has drastically increased speed and reliability. The development of switched Ethernet technology has also eliminated the issue of transmission collisions, making Ethernet much more predictable and suitable for real-time applications. Moreover, Ethernet equipment manufacturers are now producing hardware specifically tailored for industrial environments, ensuring durability, safety, and compatibility with field devices.
Ethernet offers several advantages that make it a compelling choice for industrial communication:
1. **Widespread Adoption and Support**: Ethernet is the most commonly used network technology in the world, supported by nearly all major programming languages, including Java, C++, and Visual Basic. This broad support ensures a rich ecosystem of tools and development environments, making it easier to implement and maintain.
2. **Cost-Effective**: Due to its widespread use, Ethernet hardware is widely available and relatively inexpensive. Network cards for Ethernet cost only a fraction of those for specialized fieldbuses like Profibus or FF. As integrated circuit technology advances, these costs are expected to decrease even further.
3. **High Communication Speed**: Modern Ethernet technologies, such as 100M Fast Ethernet, 1Gbps Gigabit Ethernet, and 10Gbps Ethernet, offer significantly higher speeds than traditional fieldbuses. This makes Ethernet well-suited for high-bandwidth applications and future-proofing industrial systems.
4. **Abundant Resources and Expertise**: Ethernet has been in use for decades, and there is a wealth of experience and knowledge in its design and implementation. This availability of skilled professionals and software tools reduces development time and lowers overall project costs.
5. **Strong Potential for Future Development**: With its broad application across industries, Ethernet continues to receive significant investment and innovation. As information and communication technologies evolve rapidly, Ethernet is well-positioned to keep pace, ensuring long-term technical sustainability.
By adopting Ethernet as the communication platform in industrial control systems, the fieldbus can remain aligned with mainstream computer networking trends. This integration allows for mutual growth between fieldbus technologies and other network solutions, avoiding the need for isolated research and development. In the future, industrial control networks will likely evolve into more interconnected, efficient, and scalable systems, as illustrated in Figure 4.1.
Dark gray Transmitting Antenna,B01 Dark gray Receiving Antenna,B01 Dark gray Directional Antenna
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