Hot-Swappable Daisy-Chain I/O Modules Without Bus Reset
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Solution Overview
Problem
Existing flexible expandable automation systems using daisy-chain I/O-bus technology face interruptions in communication when an I/O-unit is unplugged or faulty, requiring a system reset and power down for module exchanges, which is time-consuming and laborious.
Innovation Solution
Incorporating a hot-swap control unit within each I/O-module carrier that automatically bridges the daisy chain and manages the daisy-chain control signals, allowing for seamless module swapping without system reset or power down, utilizing a micro-controller or ASIC for active control and communication with the I/O bus master.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an I/O-unit is unplugged or faulty in a daisy-chain I/O-bus system, then communication is interrupted and system reset is required, but this causes time loss and operational interruption
Solution Approach 1:
The patent introduces a bridge unit as an intermediary component that automatically detects interruptions in the daisy-chain I/O-bus and establishes alternative communication paths. When an I/O-unit is unplugged or faulty, the bridge unit mediates by routing signals through alternative paths, preventing communication interruption and eliminating the need for system reset.
Solution Approach 2:
The system dynamically adapts its communication topology by detecting faults in real-time and reconfiguring the signal paths automatically. The bridge unit monitors the status of I/O-units and dynamically switches between different communication routes, maintaining continuous operation without requiring static pre-planning of fault tolerance.
2Ease of operation
If module exchange requires power down and system reset, then proper error handling is ensured, but operational continuity is lost
Solution Approach 1:
The bridge unit performs preliminary error detection and path preparation before actual module exchange occurs. By pre-configuring alternative communication paths and detecting potential issues in advance, the system can handle module exchanges without interruption, as the error handling infrastructure is already in place and activated.
Solution Approach 2:
The system maintains continuous operational action during module exchanges by using the bridge unit to sustain communication flows. The useful action of data transmission and control signaling continues uninterrupted through alternative paths, allowing module exchange to occur without stopping the overall system operation.
3Reliability
If a bridge unit is introduced to maintain daisy-chain integrity, then communication continuity is improved, but device complexity increases
Solution Approach 1:
The bridge unit is designed with multi-functionality, serving as both a normal I/O-bus participant and a fault-tolerance mechanism. It can operate in multiple modes: normal signal transmission, fault detection, and alternative path routing. This universal design reduces the need for separate dedicated fault-handling components, thereby limiting the increase in overall system complexity.
Solution Approach 2:
The bridge unit implements self-service by automatically detecting faults and reconfiguring communication paths without external intervention. The system monitors itself and performs self-healing operations, eliminating the need for complex external control mechanisms or manual fault handling procedures, thus keeping the added complexity manageable.
Data Source
AI summary
A flexible expandable automation device includes: a main control unit; and at least two I/O-units connected to the main control unit and to each other via an I/O-bus. The I/O-bus works according to a daisy-chain technique. The I/O-bus has a bus signal line and a daisy-chain-control-line. Each I/O-unit has a daisy-chain-control-IN-port for receiving a daisy-chain-control-signal as a daisy-chain-control-IN-signal and a daisy-chain-control-OUT port for delivering the daisy-chain-control-signal as a daisy-chain-control-OUT-signal to a next adjacent I/O-unit. Each I/O-unit has an I/O-module carrier and a pluggable and unpluggable I/O-module. The daisy-chain-control-IN-port and the daisy-chain-control-OUT-port are part of the I/O-module carrier. Each I/O-module-carrier has a hot-swap-control unit that, in case of an unplugged I/O-module creating an interrupted daisy chain, automatically bridges the interrupted daisy chain.