8B/10B Encoding for PLC Module Addressing

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Solution Overview

Problem

Control systems, particularly those using programmable logic controllers (PLCs), are susceptible to faults due to equipment failure and data transmission errors, especially in communication between modules and devices, which can lead to inefficiencies and errors in real-time operations.

Innovation Solution

A system utilizing 8B/10B encoded frames with specific ordered fields for communication between PLCs and modules, including a transmission circuit and receiving circuit, to ensure reliable and error-detecting data transmission, and implementing watchdog timers for fault detection and recovery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional data transmission methods are used in PLC communication, then device complexity is reduced, but data transmission reliability deteriorates due to susceptibility to errors and faults

Engineering Contradiction:
Improvedata transmission reliabilityVSAvoidcommunication protocol complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary encoding mechanism (8B/10B encoding) that acts as a mediator between the data source and destination. This encoding scheme adds redundant bits to detect and correct transmission errors, thereby improving reliability without requiring complex error handling logic at the application layer. The encoding itself serves as the error-detection mechanism, resolving the contradiction between reliability and complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies error-detection encoding (8B/10B) preliminarily to the data before transmission occurs. By pre-encoding the data with redundancy bits that enable error detection, the system proactively prepares for potential transmission errors rather than reacting to them after occurrence. This preliminary action improves reliability while keeping the overall system complexity manageable through standardized encoding procedures.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If error detection and recovery mechanisms are implemented, then fault tolerance improves, but device complexity increases

Engineering Contradiction:
Improvefault toleranceVSAvoiderror handling complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The 8B/10B encoding scheme serves as an intermediary that automatically provides error detection capabilities. The encoding process embeds redundancy information that enables the receiver to detect transmission errors without requiring complex error-detection algorithms. This intermediary mechanism improves fault tolerance while maintaining relatively simple implementation through standardized encoding tables and procedures.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The error-detection capability is built into the encoding scheme itself, allowing the data to essentially detect its own errors through the redundancy embedded during encoding. The receiver can identify errors by checking the encoded data against the encoding rules, providing self-service error detection without requiring external validation mechanisms or complex error-handling software.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If real-time communication is enabled with error detection, then operational accuracy improves, but data transmission speed decreases

Engineering Contradiction:
Improvedata transmission accuracyVSAvoiddata transmission speed
Core Design Contradiction:
Measurement precisionVSSpeed

Solution Approach 1:

The patent changes the parameter of data representation from raw binary to 8B/10B encoded format. This parameter change increases the data size by 25% (from 8 to 10 bits per byte) to enable error detection, thereby improving transmission accuracy. The trade-off in speed is accepted as a necessary consequence of achieving real-time reliable communication in industrial PLC systems where accuracy is prioritized over maximum theoretical throughput.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2057515B1Devices, systems, and methods for assigning a PLC module address
Publication Date: 2018.05.02 SIEMENS INDUSTRY INC
  • EP2057515B1 patent drawingFigure 1
  • EP2057515B1 patent drawingFigure 2
  • EP2057515B1 patent drawingFigure 3

AI summary

Certain exemplary embodiments can comprise a system, which can comprise a module communicatively coupled to a programmable logic controller (PLC). The module can comprise a transmission circuit and/or a receiving circuit. The module can be adapted to communicate with the PLC via 8B/10B encoded frames. A frame of the 8B/10B encoded frames can comprise a plurality of ordered fields.