PLC Power-Shutdown Notification Over Existing Communication Lines
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Solution Overview
Problem
Control apparatuses, such as programmable controllers (PLCs), face challenges in maintaining safe operations and fault tolerance during power shutdowns, as existing solutions require dedicated notification lines, which are costly and complex.
Innovation Solution
A control apparatus with an arithmetic operation device, a communication circuit, a processor, and a monitoring circuit that detects power shutdowns and sends a specific notification frame through a communication line to functional units, allowing them to transition to a safe operation state, thereby eliminating the need for dedicated notification lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated notification lines are used to notify functional units of power shutdown, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines the power shutdown notification function with the existing communication line used for normal data exchange between the arithmetic operation device and functional units. Instead of using separate dedicated notification lines, the system transmits shutdown notification frames through the existing communication infrastructure, thereby merging multiple functions into a single channel and reducing overall system complexity while maintaining reliability.
Solution Approach 2:
The communication line is designed to serve multiple purposes: normal operational data exchange and power shutdown notifications. The notification frame format is standardized to be compatible with existing communication protocols, allowing the same physical infrastructure to handle both routine communication and emergency shutdown signaling, thus eliminating the need for specialized dedicated lines.
2Reliability
If dedicated notification lines are used for power shutdown notification, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the shutdown notification function into the existing communication line infrastructure, eliminating the need to manufacture and install separate dedicated notification lines. This reduces material costs, installation expenses, and system complexity while ensuring that functional units receive reliable shutdown notifications through the already-deployed communication network.
3Device complexity
If power shutdown notification is transmitted through communication line, then device complexity is reduced, but response time may be delayed
Solution Approach 1:
The system employs a monitoring circuit that continuously monitors the power supply state and is prepared to detect power shutdown conditions immediately when they occur. This preliminary monitoring ensures that shutdown notification frames can be transmitted without delay through the communication line as soon as a power failure is detected, minimizing response time while using the existing communication infrastructure.
Solution Approach 2:
The patent implements a priority mechanism where power shutdown notification frames are given highest priority transmission status. When a shutdown condition is detected, the notification frame is transmitted immediately, skipping normal communication protocols and procedures that would otherwise cause delays. This ensures rapid notification to functional units despite using the standard communication line infrastructure.
Data Source
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Figure 3A~3B
AI summary
An arithmetic operation device configuring a control apparatus includes: a communication circuit that is used for exchanging data with functional units through a communication line; a processor that is used for executing a user program executing at least one of an arithmetic operation process using data acquired from the functional units and a generating process of data to be transmitted to the functional units; and a monitoring circuit that is connected to the communication circuit and the processor. The monitoring circuit gives a notification from the communication circuit to the functional units on the basis of at least one of detection of shutoff of power supplied to the arithmetic operation device and reception of a preliminary notification before the shutoff of the power supplied to the arithmetic operation device, and the notification is used for executing a process according to shutoff of power supply to the arithmetic operation device.