# US 9,798,611 B2 · Programmable logic controller > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,798,611 B2 - Document ID: US9798611B2 - Status: Granted - Kind: B2 - Application number: 14/904,966 - Filed: 2014-04-25 - Published: 2016-09-01 - Granted: 2017-10-24 - Earliest claimed: 2014-04-25 - Assignees: Mitsubishi Electric Corporation - Applicants: Mitsubishi Electric Corporation - Inventors: Kazuhiro Nakaminami - Web page: https://patentgrep.com/patent/US9798611B2 ## CPC - G06F 11/0793: {Remedial or corrective actions (recovery from an exception in an instruction pipeline G06F9/3861; by retry G06F11/1402; for recovering from a failure of a protocol instance or entity H04L69/40)} - G05B 19/058: {Safety, monitoring} - G06F 11/0736: {in functional embedded systems, i.e. in a data processing system designed as a combination of hardware and software dedicated to performing a certain function (testing or monitoring of automated control systems G05B23/02)} - G06F 11/0751: {Error or fault detection not based on redundancy (power supply failures G06F1/30; network fault management H04L41/06)} - G06F 11/0772: {Means for error signaling, e.g. using interrupts, exception flags, dedicated error registers} - G06F 11/0787: {Storage of error reports, e.g. persistent data storage, storage using memory protection} - G06F 11/079: {Root cause analysis, i.e. error or fault diagnosis (in a hardware test environment G06F11/22; in a software test environment G06F11/36)} - G05B 2219/14107: Recovery, after detection or reconfiguration, effect an error eliminati - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - 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) ## Abstract A programmable logic controller includes an error detection unit, a data memory storing error occurrence information indicating, for each error kind, whether the error detection unit has detected an error, an error automatic cancellation processing unit determining whether an error factor of each error has been eliminated and, when the error factor has been eliminated, performing an error cancellation process including a process to change the error occurrence information to error non-occurrence, and an error-automatic-cancellation-permission determination unit referring to an error automatic cancellation permission setting and determining, when the error detection unit detects an error, whether the error is canceled by the error automatic cancellation processing unit on the basis of the error automatic cancellation permission setting, wherein the error automatic cancellation processing unit performs the error cancellation process on the error that the error-automatic-cancellation-permission determination unit has determined that the error automatic cancellation processing unit is to cancel. ## Claims ### Claim 1 A programmable logic controller capable of executing a control program on a basis of a signal input from an apparatus connected to the programmable logic controller, the programmable logic controller comprising: an error detection unit that detects an error that occurs while the control program is being executed; a storage unit that stores error occurrence information indicating, for each error kind, whether or not the error detection unit has detected an error; an error-cancellation-permission-setting storage unit that stores information indicating whether or not each error that the error detection unit detects is an error capable of being automatically canceled; an error cancellation permission determination unit that, when the error detection unit detects an error, determines whether or not the error is an error capable of being automatically canceled on a basis of information stored in the error-cancellation-permission-setting storage unit; an error cancellation processing unit that determines whether or not an error factor has been eliminated for an error that the error cancellation permission determination unit determines to be an error capable of being automatically canceled and, when the error factor has been eliminated, automatically performs an error cancellation process including a process to change the error occurrence information to non-occurrence of an error; and a notification device that issues a notification that indicates that an error is occurring when the error detection unit detects the error the error cancellation process includes a process to cancel a notification that is issued from the notification device indicating that an error is occurring and a process to record, in an internal memory or an external memory attached to the programmable logic controller, information indicating that the process to change the error occurrence information to non-occurrence of an error has been performed, wherein the information is stored in the error-cancellation-permission-setting storage unit prior to executing error detection by the error detection unit. ### Claim 2 (depends on 1) The programmable logic controller according to claim 1, further comprising a data update unit that performs a process to update a setting content to be stored in the error-cancellation-permission-setting storage unit independently from execution of the control program. ### Claim 3 (depends on 1) The programmable logic controller according to claim 1, wherein the information stored in the error-cancellation-permission-setting storage unit comprises a group field for a group of errors and an individual field for each of the errors, which are set to indicate whether automatic cancellations of the respective error are permitted. ### Claim 4 (depends on 1) The programmable logic controller according to claim 1, wherein, for each error that the automatic cancellation is permitted based on the information in the error-cancellation-permission-setting storage unit, the error cancellation processing unit periodically automatically determines if the respective error is no longer occurring based on whether the error factor has been eliminated without user input and in response to the determining that the respective error is no longer occurring, automatically clears the error by executing the error cancellation process and wherein the storage unit further stores a cancellation history comprising information regarding occurrence of the error and respective automatic cancellation. ### Claim 5 A programmable logic controller capable of executing a control program on a basis of a signal input from an apparatus connected to the programmable logic controller, the programmable logic controller comprising: an error detection unit that detects an error that occurs while the control program is being executed; a storage unit that stores error occurrence information indicating, for each error kind, whether or not the error detection unit has detected an error; an error-cancellation-permission-setting storage unit that stores information indicating whether or not each error that the error detection unit detects is an error capable of being automatically canceled; an error cancellation permission determination unit that, when the error detection unit detects an error, determines whether or not the error is an error capable of being automatically canceled on a basis of information stored in the error-cancellation-permission-setting storage unit; an error cancellation processing unit that determines whether or not an error factor has been eliminated for an error that the error cancellation permission determination unit determines to be an error capable of being automatically canceled and, when the error factor has been eliminated, automatically performs an error cancellation process including a process to change the error occurrence information to non-occurrence of an error; and a notification device that issues a notification that indicates that an error is occurring when the error detection unit detects the error, wherein the error cancellation process includes a process to cancel a notification that is issued from the notification device indicating that an error is occurring and a process to transmit, to an external apparatus, information indicating that the process to change the error occurrence information to non-occurrence of an error has been performed, wherein the information is stored in the error-cancellation-permission-setting storage unit prior to executing error detection by the error detection unit. ### Claim 6 (depends on 5) The programmable logic controller according to claim 5, further comprising a data update unit that performs a process to update a setting content to be stored in the error-cancellation-permission-setting storage unit independently from execution of the control program. ### Claim 7 A programmable logic controller capable of executing a control program on a basis of a signal input from an apparatus connected to the programmable logic controller, the programmable logic controller comprising: an error detection unit that detects an error that occurs while the control program is being executed; a storage unit that stores error occurrence information indicating, for each error kind, whether or not the error detection unit has detected an error; an error-cancellation-permission-setting storage unit that stores information indicating whether or not each error that the error detection unit detects is an error capable of being automatically canceled; an error cancellation permission determination unit that, when the error detection unit detects an error, determines whether or not the error is an error capable of being automatically canceled on a basis of information stored in the error-cancellation-permission-setting storage unit; an error cancellation processing unit that determines whether or not an error factor has been eliminated for an error that the error cancellation permission determination unit determines to be an error capable of being automatically canceled and, when the error factor has been eliminated, automatically performs an error cancellation process including a process to change the error occurrence information to non-occurrence of an error; and a data update unit that performs a process to update a setting content to be stored in the error-cancellation-permission-setting storage unit independently from execution of the control program, wherein the information is stored in the error-cancellation-permission-setting storage unit prior to executing error detection by the error detection unit.