Safety Switch Configuration via Shift Registers and Check Bits
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Solution Overview
Problem
Existing safety switching devices lack a simple and fail-safe method for configuring operating parameters, often requiring redundant hardware resources and risking incorrect configurations due to limited input options and error detection mechanisms.
Innovation Solution
A safety switching device with a large number of switch elements and a method using a readout device connected to shift registers to serially transmit switch positions, generating check bits for integrity verification, allowing configuration with minimal hardware resources and reducing error risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant reading processes are used to ensure error tolerance, then reliability is improved, but hardware resources are consumed
Solution Approach 1:
The patent introduces a readout device with shift registers as an intermediary component between the DIP switches and the microcontroller. This mediator serially reads the switch positions and transmits them to the microcontroller, eliminating the need for the microcontroller to directly read multiple switches through multiple GPIO pins. The shift registers handle the redundant reading process internally, freeing up microcontroller hardware resources while maintaining reliability through serial transmission with error detection.
Solution Approach 2:
The patent replaces the traditional parallel reading mechanism (where the microcontroller directly reads multiple DIP switches through multiple GPIO pins) with a serial reading mechanism using shift registers. This substitution transforms the hardware architecture from a parallel interface requiring multiple GPIO pins to a serial interface requiring only a single GPIO pin, significantly reducing hardware resource consumption while maintaining the ability to detect reading errors through redundant verification.
2Reliability
If communication protocols with error detection are used, then reliability is improved, but hardware resources are consumed
Solution Approach 1:
The patent combines the error detection functionality with the existing dual-channel microcontroller architecture. The readout device serially transmits the switch positions, and the microcontroller uses its existing redundant processing capability to verify the received data. This merging approach allows error detection without requiring additional dedicated hardware resources for communication protocols, as the error detection leverages the already-present dual-channel architecture.
3Adaptability or versatility
If multiple switch positions are configured, then adaptability is improved, but error risk increases
Solution Approach 1:
The patent implements a feedback mechanism where the readout device serially transmits the switch positions to the microcontroller, which then verifies the received data using check bits and redundant processing. This feedback loop allows the system to detect and reject incorrect configurations, thereby reducing error risk even as the number of configurable switch positions increases. The feedback mechanism ensures that adaptability is maintained while reliability is protected through automated error detection.
4Reliability
If manual parity bit generation is used, then error detection is improved, but device complexity increases
Solution Approach 1:
The patent implements self-service error detection where the system automatically generates and verifies check bits without requiring manual user intervention. The readout device serially transmits the switch positions along with automatically generated check bits, and the microcontroller automatically verifies the data integrity. This eliminates the need for users to manually configure parity bits, reducing device complexity from the user's perspective while maintaining robust error detection capabilities.
Data Source
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AI summary
A safety switching device (10) is described, comprising a plurality of switching elements (24; S0...S9) for setting at least one operating parameter of the safety switching device (10) and a control and evaluation unit (20; 20a-b) configured to set the operating parameter based on the switch positions of the switching elements (24; S0...S9). A readout device (26) is provided between the switching elements (24; S0...S9) and the control and evaluation unit (20; 20a-b), comprising at least one shift register (28A-B) connected to at least one first input (A0..A7; B0..B7) by the switching elements (24; S0...S9).S9) and is connected to the control and evaluation unit (20; 20a-b) via an output (QB), wherein an output (QB) of the shift register (28A-B) is fed back to a second input (SIA) of the shift register (28A-B) via a logic element (30) to generate check bits, and wherein the control and evaluation unit (20; 20a-b) is configured to check the integrity of the switch positions (24; S0..S9) read by means of the read device (26) using the check bits.