# US 10,564,636 B2 · Method and arrangement for operating two redundant systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,564,636 B2 - Document ID: US10564636B2 - Status: Granted - Kind: B2 - Application number: 16/032,433 - Filed: 2018-07-11 - Published: 2019-01-17 - Granted: 2020-02-18 - Earliest claimed: 2017-07-13 - Assignees: Siemens Aktiengesellschaft - Applicants: Siemens Aktiengesellschaft - Inventors: Thomas Grosch; Walter Maximilian - Web page: https://patentgrep.com/patent/US10564636B2 ## CPC - G05B 23/0221: {Preprocessing measurements, e.g. data collection rate adjustment; Standardization of measurements; Time series or signal analysis, e.g. frequency analysis or wavelets; Trustworthiness of measurements; Indexes therefor; Measurements using easily measured parameters to estimate parameters difficult to measure; Virtual sensor creation; De-noising; Sensor fusion; Unconventional preprocessing inherently present in specific fault detection methods like PCA-based methods} - G05B 9/03: with multiple-channel loop, i.e. redundant control systems - G05B 19/0425: {Safety, monitoring} - G05B 19/0428: {Safety, monitoring (G05B19/0423 takes precedence)} - G06F 11/202: {where processing functionality is redundant (redundant communication control functionality G06F11/2005, redundant storage control functionality G06F11/2089)} - G05B 2219/24182: Redundancy - G05B 2219/24195: Compare data in channels at timed intervals, for equality - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract A method and an arrangement having redundant systems operating in parallel in a cyclic mode and reciprocally checking a result of the task of the other system on a regular basis, and wherein one system is selected or confirmed for the productive mode in the fault situation found, where a characteristic variable concerning an operating parameter is picked up for each of the systems in multiple/all cycles and used for updating statistical parameters, where at least when a disparity between results of the two systems is found, a current operating parameter is correlated with the statistical parameter for each system, and where the system for which the current operating parameter differs from the statistical parameter less is detected as the correctly operating system and used for the productive mode such that the degree of fault coverage can be increased and hence the availability of the overall system increased. ## Claims ### Claim 1 A method for operating an arrangement having two redundant programmable logic controllers each operating in parallel in a cyclic mode, one programmable logic controller of the two programmable logic controllers operating in a productive mode each time and another programmable logic controller of the two programmable logic controllers executing the same task for checking purposes, the method comprising: checking reciprocally by the two programmable logic controllers at least one result of a task of a respective other system on a regular basis, each programmable logic controller of the two programmable logic controllers comparing a result of the task of the other programmable logic controller of the two programmable logic controllers with their own result, a detected fault comprising a detected disparity among the results leads to a fault situation being found, with one of the two programmable logic controllers being selected or confirmed for the productive mode in the fault situation found; picking up at least one respective characteristic variable concerning an operating parameter for each of the two programmable logic controllers in multiple or all cycles and using the picked up at least one respective characteristic variable for updating at least one statistical parameter each time; correlating a current operating parameter with the associated statistical parameter for each programmable logic controller at least when a disparity between the results of the two programmable logic controllers is found; and utilizing the programmable logic controller for which the respective current operating parameter differs from the associated statistical parameter less is detected as the correctly operating programmable logic controller as the productive mode. ### Claim 2 (depends on 1) The method as claimed in patent claim 1, wherein the operating parameter used comprises a program runtime comprising a runtime for executing a complete cycle or a program part executed in a cycle each time. ### Claim 3 (depends on 1) The method as claimed in claim 1, wherein the operating parameter used is at least one performance counter for specifying a performance index of the respective programmable logic controller. ### Claim 4 (depends on 1) The method as claimed in claim 1, wherein a multiplicity of characteristic variables are picked up as operating parameters and combined to form one of (i) a set of statistical parameters and (ii) a single overall statistical parameter. ### Claim 5 (depends on 1) The method as claimed in claim 1, wherein commands for picking up the operating parameters are inserted in an application program of the two programmable logic controllers that is executed in each cycle. ### Claim 6 (depends on 5) The method as claimed in patent claim 5, wherein the commands are inserted in a number of program blocks that are executed independently of branches or conditions in each cycle. ### Claim 7 An arrangement comprising: two programmable logic controllers which operate in parallel in a cyclic mode, one programmable logic controller of the two programmable logic controllers being switched to a productive mode each time and another programmable logic controller of the two programmable logic controllers executing the same task for checking purposes; wherein, by virtue of a respective result of a task of a respective other programmable logic controller of the two programmable logic controllers is compared with their own result of the task by the two programmable logic controllers to reciprocally check results of the respective other programmable logic controller on a regular basis; wherein one of (i) a detected fault and (ii) a detected disparity among the results leads to a fault situation being found; wherein one programmable logic controller of the two programmable logic controllers is one of (i) selected for the productive mode and (ii) confirmed for the productive mode in the fault situation; wherein at least one respective characteristic variable concerning an operating parameter is picked up for each of the two programmable logic controllers in multiple or all cycles and used to update at least one statistical parameter each time; wherein, at least when a disparity between the results of the two programmable logic controllers is found, a current operating parameter is correlated with the associated statistical parameter for each programmable logic controller; and wherein the programmable logic controller for which the respective current operating parameter differs from the associated statistical parameter less is detected as the correctly operating programmable logic controller and used for the productive mode. ### Claim 8 (depends on 7) The arrangement as claimed in claim 7, wherein the operating parameter used forms a program runtime comprising a runtime for executing a complete cycle or a program part executed in a cycle each time. ### Claim 9 (depends on 7) The arrangement as claimed in claim 7, wherein the operating parameter used is at least one performance counter for specifying a performance index of the respective programmable logic controller. ### Claim 10 (depends on 8) The arrangement as claimed in claim 8, wherein the operating parameter used is at least one performance counter for specifying a performance index of the respective programmable logic controller. ### Claim 11 (depends on 7) The arrangement as claimed in claim 7, wherein a multiplicity of characteristic variables to be picked up as operating parameters are combined to form one of (i) a set of statistical parameters and (ii) a single overall statistical parameter. ### Claim 12 (depends on 8) The arrangement as claimed in claim 8, wherein a multiplicity of characteristic variables to be picked up as operating parameters are combined to form one of (i) a set of statistical parameters and (ii) a single overall statistical parameter. ### Claim 13 (depends on 9) The arrangement as claimed in claim 9, wherein a multiplicity of characteristic variables to be picked up as operating parameters are combined to form one of (i) a set of statistical parameters and (ii) a single overall statistical parameter. ### Claim 14 (depends on 7) The arrangement as claimed in claim 7, wherein commands for picking up operating parameters are inserted in an application program of the two programmable logic controllers which is executed in each cycle. ### Claim 15 (depends on 14) The arrangement as claimed in claim 14, wherein the commands to be inserted in a number of program blocks are executed independently of branches or conditions in each cycle.