PLC Shared Cable Interrupt Signal Collision Avoidance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional programmable logic controllers (PLCs) face complexities in data transmission cable configuration due to one-to-one connections between control modules and communication modules, leading to delayed data transmission and errors when sharing a communication line.
Innovation Solution
Implementing a PLC design where communication modules check interrupt signals to alternately transmit data without collision through a shared data transmission cable, allowing each module to disable data transmission by applying an interrupt signal to prevent collisions and errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If communication lines are connected one-to-one between control module and communication modules, then data transmission reliability is improved, but device complexity and cable configuration complexity increase
Solution Approach 1:
The patent merges multiple communication lines into a single shared communication line that is time-shared among multiple communication modules. Instead of providing separate dedicated cables for each communication module, the system combines them into one physical cable with multiple logical channels, thereby reducing cable complexity while maintaining reliable data transmission through time-division multiplexing.
Solution Approach 2:
The shared communication line serves multiple functions by accommodating data transmission from multiple different communication modules. A single cable infrastructure is designed to handle communications from various modules sequentially, making the communication system universal and adaptable to multiple sources without requiring dedicated infrastructure for each.
2Device complexity
If communication line is shared by multiple communication modules, then device complexity is reduced, but data transmission errors and collisions increase
Solution Approach 1:
The system implements periodic time-division multiplexing where each communication module is allocated specific time slots for data transmission. The control module periodically cycles through connected communication modules in a predetermined order, allowing each module to transmit data during its designated period. This periodic structure prevents collisions by ensuring only one module transmits at a time while maintaining simple shared cable infrastructure.
Solution Approach 2:
The control module implements feedback mechanisms to manage the shared communication line. By monitoring which communication modules need to transmit data and coordinating their access sequentially, the system receives feedback about data transmission needs and adjusts the timing and order of communications accordingly, preventing collisions and ensuring reliable data transfer over the shared cable.
3Device complexity
If data transmission follows predetermined transmission order, then device complexity is reduced, but data transmission speed and productivity decrease
Solution Approach 1:
While maintaining a predetermined transmission order framework, the system dynamically adjusts the timing and scheduling of data transmissions based on actual data availability and priority needs. The control module can flexibly manage the sequence and timing of communications with different modules, allowing high-priority or time-sensitive data to be transmitted sooner within the established protocol structure, thus improving overall data transmission productivity without increasing system complexity.
Data Source
AI summary
The PLC according to the present disclosure includes a control module configured to perform a control operation according to a preset program; a first communication module configured to transmit a control command from the control module to at least one of first external devices; and a second communication module configured to transmit the control command from the control module to at least one of second external devices, wherein the first and second communication modules transmit external data to the control module via a data transmission cable which is shared with each other, and check interrupt signals therebetween to alternately transmit the external data to the control module, respectively.