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Introduction to Industrial Local Networks

• Course: Industrial Engineering & Logistics 2
• Instructor: Pr. ZBAKH Douae
• University: Université Abdelmalek Essaâdi
• Institution: ENSA de Tanger

Chapter II: Industrial Local Networks - Industrial Environment

• Focuses on industrial local networks (RLI)
• The industrial environment presents specific needs for RLI
• Key requirement: Reliable and fast data transmission during manufacturing processes

Plan

• Global Requirement
• Physical Aspects
• MAC Sublayer
• LLC Sublayer

Global Requirements: Introduction

• Industrial environments necessitate specific requirements for RLI
• Manufacturing processes require fast and error-free program uploads to programmable automation devices.
• Data transmission must be secure.

Global Requirements: Introduction (continued)

• Data transmission security is paramount.
• A process for error detection in data transmission is implemented by sensors.
• Data is transmitted securely to prevent data loss or corruption.

Global Requirements: Introduction (continued)

• Task management is crucial in industrial environments
• A dedicated cell controller is needed to manage all tasks & numeric controls.

Global Requirements: Introduction (continued)

• Supervision is vital for continuous production
• Disturbances in the physical environment must be avoided
• The production chain’s proper functioning must be ensured

Global Requirements: Introduction Diagram

• Usine (Factory): Non-critical transmission time (Tr)
• Atelier (Workshop): Tr < 1 second
• Terrain (Field): Tr < 0.01 second

Global Requirements: OSI and RLI

• Presentation of the OSI model
• Each layer adds its header to the data.

Global Requirements: OSI and RLI (Continued)

• Functions of each layer in the OSI model
• Application: Interface with applications
• Presentation: Data representation
• Session: Data synchronization
• Transport: Connection
• Network: Routing & delivery
• Data link: Frame building
• Physical: Bit encoding

Global Requirements: OSI and RLI (Continued)

• Reduced OSI model.
• Shows the connection between OSI layers and RLI layers.
• Key layers: Application, Data Link, Physical

Global Requirements: OSI and RLI (Continued)

• Functions of the application layer of the OSI model: Implementation of applications, control, and necessary interfaces for communication.
• Data link layer: Error correction, reliable communication
• Three types of LLC protocols: LLC1 (connectionless, acknowledgment-less), LLC2 (connection-oriented, acknowledgment-based), LLC3 (connectionless-acknowledgment-based)

Physical Aspects

• Topology types and their advantages and disadvantages are covered
• (Star, Bus, Ring)
• Important properties of physical layer include topology
• Physical support types (copper, fiber optic, wireless)
• Transmission rates, maximum length, number of nodes, and power supply.

Physical Aspects: Topology Types

• Covered topology types include star, bus, and ring.

Physical Aspects: Topology (continued)

• Star: Advantages include multiple parallel communications, simple wiring. Disadvantages include routing & varying signal path lengths.
• Bus: Advantages include direct communication, no routing required. Disadvantages involve medium access control.
• Ring: Advantages include simple cabling. Disadvantages include routing and varying signal path lengths, different path lengths.

Physical Aspects: Topology Examples

• Diagrams showing bus and star architectures, ring as well.

Physical Aspects: Topology Problems

• Network collision issues in bus topologies. This happens when multiple nodes attempt to transmit data simultaneously on a shared physical line.

Physical Aspects: Transmission Support

• Different transmission mediums: copper, fiber optic, and wireless media. Their advantages and disadvantages are summarized.

Physical Aspects: Transmission Support (continued)

• Copper: Low cost. Susceptible to electromagnetic interference (EMI).
• Fiber Optic: High cost. Less susceptible to EMI. Higher bandwidth (capacity).
• Wireless: Good mobility & flexibility, highly susceptible to interference.

Physical Aspects: Transmission Support

• Coaxial cable types are discussed.
• Thin coaxial: Used with 10Base2 protocol.
• Thick coaxial: Used with 10Base5 protocol, less susceptible to EMI.

Physical Aspects: Transmission Support (continued)

• Fiber optic cables: A preferred choice in environments with high electromagnetic interference

Physical Aspects: Transmission Support (continued)

• Twisted-pair cables: Advantages & disadvantages
• Types of twisted pair cabling: UTP (unshielded), FTP (foiled), SFTP (shielded foiled twisted pair), & STP (shielded) cables.

Physical Aspects: Transmission Support (continued)

• Industrial cables are reinforced based on conditions encountered(heat, chemicals, etc).
• Examples of reinforced cables are shown.

Physical Aspects: Transmission Support (continued)

• Industrial networking requires additional protection. Network interfaces and connections must be protected from harsh environmental conditions and interference.

Physical Aspects: Encoding

• Need for transmission channel and reliability method
• Methods to minimize transmission errors: Limiting bandwidth to reduce interference and using band-based encoding techniques.

Physical Aspects: Encoding

• Source encoder's task: Encode the source output into binary sequence, achieving efficiency.
• Channel encoder's task: Ensure faithful reproduction of the binary sequence through noisy channels, mitigating interference.

Physical Aspects: Encoding (continued)

• Bit Stuffing: Used to ensure the reliability of messages in a transmission

Physical Aspects: Encoding (continued)

• Manchester encoding: Guarantees synchronisation between sender and receiver to minimise signal gaps. Ensures consistent signal transmission

Physical Aspects: Encoding Diagrams

• Diagrams illustrating Bit Stuffing and Manchester II encoding schemes

Data Link Layer: MAC sublayer

• Real-time capabilities: Transmission within a precise, known time frame.
• Deterministic networks: Networks without random delays in data access methods are deterministic.

Data Link Layer: MAC sublayer

• Prioritized and hierarchical access is necessary. Priority is given to critical information during transmissions in industrial environments.

Data Link Layer: MAC sublayer (Polling method)

• Master/Slave mechanism: Master device initiates communication with slave devices.

Data Link Layer: MAC sublayer (continued)

• Master/slave method: Details this communication mechanism.

Data Link Layer: MAC sublayer (continued)

• Token Passing algorithm: Uses a token to define who is allowed to transmit on the network at any given time. This transmission method avoids collisions unlike the master/slave method

LLC sublayer (Logical Link Control)

• LLC layer provides services between the MAC sublayer and the application layer.
• Guarantees message delivery, error detection, and recovery.

LLC Sublayer (continued)

• SAP (Service Access Point) is each point of access that facilitates application layer access to data link services.

LLC sublayer (continued)

• The LLC1 service only supports commands for transmitting data.

LLC sublayer (continued)

• The LLC2 service supports functions of establishing, maintaining and ending connection as well as handling data transmission.

LLC sublayer (continued)

• The LLC3 service is a connectionless protocol that supports acknowledgment of transmission