SLAAEM2 October   2024 AM2434

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Real-Time Communication in Factories
    2. 1.2 Industrial Protocols
    3. 1.3 Serial and Ethernet-Based Communication Protocols
  5. 2Industrial Protocols
    1. 2.1 Ethernet-Based Communication Protocols
    2. 2.2 Network Topologies
    3. 2.3 OSI Layer Model
    4. 2.4 Industrial Ethernet System Block diagram
      1. 2.4.1 Two-Port Device
      2. 2.4.2 One-Port Controller
    5. 2.5 Ethernet Physical Layer (PHY)
    6. 2.6 Media Access Controller (MAC)
      1. 2.6.1 Device MAC
      2. 2.6.2 Controller MAC
    7. 2.7 Industrial Protocol Stacks
    8. 2.8 Industrial Communication Software Development Kit (SDK)
    9. 2.9 EtherCAT Device Example Using the AM243x Processor
  6. 3Conclusion

2.1 Ethernet-Based Communication Protocols

Historically, serial-based protocols were used for factory automation due to their low cost and ease of use. Examples include DeviceNet, CanOpen, Profibus, and Modbus Serial. However, they have lower communication speeds and limited reach for high-speed communication.

With advancements in Ethernet technology, industrial Ethernet protocols like Ethernet/IP, PROFINET, and EtherCAT have become more prevalent, offering 100Mbps data rates over 100BASE-TX Ethernet. Newer protocols, such as Time-Sensitive Networking (TSN), PROFINET TSN, and CC-Link IE TSN, support 1000Mbps data rates.

Industrial Ethernet offers several advantages over traditional serial fieldbus systems:

  • Higher Data Transfer Rates and Higher Bandwidth: Ethernet supports speeds from 10Mbps to 10Gbps, compared to the lower rates of serial fieldbus. Ethernet also supports high-bandwidth applications like camera streaming, whereas serial fieldbus is limited to simpler tasks.
  • Scalability: Ethernet is easily scalable with various networking options, while serial fieldbus has fixed node limits and complex wiring.
  • Standardization: Ethernet is based on widely adopted IEEE standards and industrial Ethernet protocols are based on the Ethernet standard, with protocol specific enhancements and extensions.
  • Network Management and Diagnostics: Ethernet provides advanced tools for network monitoring and diagnostics.
  • Reduced Wiring Complexity: Ethernet requires single cable solutions without cable endpoint termination, reducing wiring complexity. Also single pair Ethernet (SPE) reduces the cable strings from 2-pair or 4-pair for standard Ethernet to 1-pair.
  • Enhanced Security Features: Ethernet includes advanced security measures, unlike the basic security of serial fieldbus. The security function requirements for industrial Ethernet are getting currently defined by the different industrial protocol organizations, as they see the need to make industrial applications within a factory secure against cyber attacks.

Furthermore, there are significant difference between industrial Ethernet and standard Ethernet. Standard Ethernet is the Ethernet type that is used in the office and IT environment. Industrial Ethernet is used in industrial applications like factory automation, grid infrastructure and building automation to exchange periodically process data.

Table 2-1 provides the benefits and differences between industrial and standard Ethernet:

Table 2-1 Benefits and Differences Between Industrial and Standard Ethernet
Industrial Ethernet Standard Ethernet
Method of data exchange Determinitic, managed frame exchange, scheduled data transmission to avoid frame collisions. Best effort, on-managed frame exchange, frame collisions
Robustness Signal immunity, harsh environments Consumer environment
Content in data process data, diagonostic data and Internet Protocol (IP) frames. IP frames with any content (video, files, web-server).
Equipment type PLC, remote IO, sensor, actuator, motor drives PC, Laptop, printer, Internet
Location Plant floor, factory, power station, building control Office network, back-end
Media Access Control (MAC) Specialized MAC implementation (ASIC, FPGA) Standard Ethernet MAC as in every PC
MAC frame processing On-the-fly and cut-though Store-and-forward
MAC error handling Error handling in MAC Error handling in OLI layer 3 and above