Single-Channel Bus Telegram for SIL2 Failsafe Data Transmission
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Solution Overview
Problem
Existing methods for achieving safety integrity level 2 in industrial automation systems require redundant hardware and processing units to maintain and transmit safety-relevant data, which increases hardware complexity and costs.
Innovation Solution
A method and system that generate a transmission telegram for one-channel transmission by storing net data in one form and its checksum in another form within a single processing unit, using bit-inverted representations and exclusive-OR operations to ensure safety integrity level 2 without the need for duplicate processing units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant hardware and processing units are used to maintain safety integrity level 2, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of two redundant processing units into a single processing unit. The first data set and second data set are maintained within the same processing unit, with the second data set being a bit-inverted representation of the first. This consolidation eliminates the need for separate redundant hardware while maintaining the ability to detect errors through comparison of the two data sets.
Solution Approach 2:
The patent changes the representation parameter of the data by creating a bit-inverted version of the original data. Instead of using identical redundant copies, the system uses data with altered bit states (inverted logic levels). This parameter change allows error detection through XOR comparison while using the same physical hardware, thus reducing device complexity while maintaining reliability.
2Reliability
If duplicate processing units are used for two-channel data transmission, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent combines the functionality of two duplicate processing units into one. A single processing unit maintains both the first data set and the second bit-inverted data set, eliminating the need to manufacture and assemble separate redundant processing units. This reduces manufacturing costs while maintaining the reliability benefits of having two data representations for error detection.
Solution Approach 2:
Instead of creating physical copies of processing units, the patent creates a logical copy in the form of a bit-inverted data set within the same processing unit. This virtual copying approach achieves the redundancy needed for safety integrity level 2 without the expense of manufacturing duplicate hardware components.
3Ease of operation
If two-channel data is maintained in the same form, then processing is simplified, but error detection capability is reduced
Solution Approach 1:
The patent applies bit-inversion to the second data set, changing its parameter representation from the original binary form to its logical inverse. This parameter transformation enables error detection capability because any discrepancy between the original data and its inverted version can be detected through XOR comparison, while the processing remains relatively simple within a single processing unit.
Data Source
AI summary
A one-channel transmission of information on a bus system within an automation system is provided. Data transmission, in compliance with safety integrity level 2 according to IEC 618508, is achieved with reduced hardware outlay. The information to be transmitted via the bus system contains net data, which is present within a processing unit in two channels in the form of a first data set and in the form of a second data set that differs from the first data set at least in the form of representation. The processing unit generates a transmission telegram suitable for one-channel transmission on the bus system from the two data sets, whereby the net data present in the form of the first data set is stored in a first data area of the transmission telegram and a checksum generated on the basis of the second data set is stored in a second data area of the transmission telegram.