Safety Controller IO Unifying Unit Power Distribution
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Solution Overview
Problem
Existing safety controllers face challenges in miniaturization and reducing the number of control points while avoiding increased wiring costs and board size, especially when adding or modifying IO units, due to the need for individual power sources and voltage monitoring components.
Innovation Solution
A safety controller with a unified IO power distribution system that eliminates the need for power-receiving terminals on each IO unit, using a single IO unifying unit to distribute power through mains and branch lines, and incorporating a voltage monitor and shutoff mechanism to manage power supply and diagnose abnormalities centrally.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual power sources and voltage monitoring components are provided for each IO unit, then power supply reliability is improved, but device complexity and wiring costs increase
Solution Approach 1:
The patent merges the power distribution function into a centralized bus structure where power is distributed through common power lines (L1, L2) rather than individual power sources per IO unit. The CPU unit integrates voltage monitoring functionality to monitor all IO units through this unified power distribution network, reducing overall system complexity while maintaining reliability through centralized control and monitoring.
Solution Approach 2:
The bus structure serves multiple functions: data communication between CPU and IO units, and power distribution to all IO units. The CPU unit's voltage monitoring circuit monitors power voltage for all IO units through this universal bus structure, eliminating the need for separate monitoring components in each IO unit.
2Productivity
If IO units are miniaturized and control points are reduced, then productivity and ease of modification are improved, but wiring duct size and cost may increase due to additional power wires
Solution Approach 1:
The patent combines power distribution with data communication by using the same bus structure for both purposes. Power lines L1 and L2 are integrated into the bus that also carries data signals, eliminating the need for separate power wiring ducts and reducing overall wiring space requirements.
Solution Approach 2:
The bus structure performs dual functions as both a data communication channel and a power distribution network. This multi-functionality allows the system to support miniaturized IO units without requiring additional dedicated power wiring space, as the existing bus infrastructure serves both purposes.
3Device complexity
If a centralized power distribution system is implemented, then device complexity is reduced, but power control precision and reliability may worsen
Solution Approach 1:
The CPU unit incorporates a voltage monitoring circuit that continuously monitors the power voltage supplied to IO units through the centralized bus. This feedback mechanism detects voltage abnormalities and enables the CPU to identify faulty IO units, maintaining power control precision and system reliability despite the simplified centralized distribution architecture.
Solution Approach 2:
The centralized power distribution system includes self-diagnosis functionality where the CPU unit autonomously monitors power voltage and identifies IO units with power supply issues. This self-service capability maintains reliability by automatically detecting and reporting problems without requiring complex external monitoring systems.
Data Source
AI summary
A safety controller of building block type has an array of a plurality of IO units each including IO circuits and a single IO unifying unit connectable to these IO units. The IO unifying unit has an IO power-receiving terminal for receiving power from an external IO power source and an IO power distributing terminal for distributing the received power to the array of IO units after passing inside the IO unifying unit. The array of IO units includes distribution mains extending along the array and having a starting end connected to the IO power distributing terminal and distribution branch lines for supplying power to each of the IO circuits inside the IO units. An IO power shutoff circuit is provided to the IO unifying unit on upstream side of the IO power distributing terminal and to each of the distribution branch lines in each of the IO units.