# US 7,752,511 B2 · Devices, systems, and methods regarding a PLC system fault > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,752,511 B2 - Document ID: US7752511B2 - Status: Granted - Kind: B2 - Application number: 11/890,894 - Filed: 2007-08-08 - Published: 2008-05-29 - Granted: 2010-07-06 - Earliest claimed: 2006-08-08 - Assignees: Siemens Industry, Inc. - Inventors: Temple L. Fulton; Lothar Trapp; Heiner Fuchs - Web page: https://patentgrep.com/patent/US7752511B2 ## CPC - G05B 19/058: {Safety, monitoring} - G05B 2219/14038: Fault in I-O racks, point level - 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 method for providing a signal indicative of a set single bit flag, which is set for a scan cycle responsive to a detection of a fault in an Input/Output (I/O) device of a programmable logic controller (PLC) system or an I/O interface of the PLC system. Numerous other aspects are provided. ## Claims ### Claim 1 A method comprising: providing a signal indicative of a set single bit flag, wherein: said flag is set for a first scan cycle in response to a detection of a fault in an Input/Output (I/O) device of a programmable logic controller (PLC) system or an I/O interface of said PLC system, and said flag is promptly reset at a conclusion of said first scan cycle; and said flag is set for a second scan cycle in response to a determination that said fault has been cleared, and said flag is promptly reset at a conclusion of said second scan cycle. ### Claim 2 (depends on 1) The method of claim 1, further comprising: detecting said fault. ### Claim 3 (depends on 1) The method of claim 1, further comprising: determining that said fault has been cleared. ### Claim 4 (depends on 1) The method of claim 1, further comprising: analyzing a message indicative of said fault; and recording information related to said fault in an entry in a log. ### Claim 5 (depends on 1) The method of claim 1, further comprising: automatically receiving said signal indicative of said flag at a user control program of a PLC of said PLC system, said user control program written in an International Electrotechnical Commission (IEC) standard 1131-3 compliant language. ### Claim 6 (depends on 1) The method of claim 1, further comprising: automatically analyzing said signal indicative of said flag via a user control program of a PLC of said PLC system, said user control program written in an International Electrotechnical Commission (IEC) standard 1131-3 compliant language. ### Claim 7 (depends on 1) The method of claim 1, further comprising: automatically responding, via a rule based action, to said signal indicative of said flag by a user control program of a PLC of said PLC system, said user control program written in an International Electrotechnical Commission (IEC) standard 1131-3 compliant language. ### Claim 8 (depends on 1) The method of claim 1, further comprising: automatically determining a history of status changes of said flag via a user control program of a PLC of said PLC system, said user control program written in an International Electrotechnical Commission (IEC) standard 1131-3 compliant language. ### Claim 9 (depends on 1) The method of claim 1, further comprising: resetting said flag for only said second scan cycle responsive to said determination that said fault has been cleared. ### Claim 10 (depends on 1) The method of claim 1, further comprising: automatically creating an event, via PLC firmware, at a PLC of said PLC system. ### Claim 11 (depends on 1) The method of claim 1, further comprising: responsive to said flag, automatically causing a system interrupt to be executed, via PLC firmware, at a PLC of said PLC system. ### Claim 12 (depends on 1) The method of claim 1, further comprising: responsive to said flag, automatically causing an object block to be executed, via PLC firmware, at a PLC of said PLC system. ### Claim 13 (depends on 1) The method of claim 1, further comprising: responsive to said flag, automatically creating a diagnostic error, via PLC firmware, at a PLC of said PLC system. ### Claim 14 (depends on 1) The method of claim 1, wherein said fault is detected via a cyclical redundancy check by said I/O device. ### Claim 15 (depends on 1) The method of claim 1, wherein said fault is detected via a cyclical redundancy check in a message transmitted from said I/O device. ### Claim 16 (depends on 1) The method of claim 1, wherein said fault is detected via a cyclical redundancy check in a message transmitted to said I/O interface. ### Claim 17 (depends on 1) The method of claim 1, wherein said fault is detected via a cyclical redundancy check by said I/O device of I/O device firmware. ### Claim 18 A machine-readable medium comprising machine instructions for activities comprising: providing a signal indicative of a set single bit flag, wherein: said flag is set for a first scan cycle in response to a detection of a fault in an Input/Output (I/O) device of a programmable logic controller (PLC) system or an I/O interface of said PLC system, and said flag is promptly reset at a conclusion of said first scan cycle; and said flag is set for a second scan cycle in response to a determination that said fault has been cleared, and said flag is promptly reset at a conclusion of said second scan cycle. ### Claim 19 A system comprising: a circuit adapted to provide a signal indicative of a set single bit flag, wherein: said flag is set for a first scan cycle in response to a detection of a fault in an Input/Output (I/O) device of a programmable logic controller (PLC) system or an I/O interface of said PLC system, and said flag is promptly reset at a conclusion of said first scan cycle; and said flag is set for a second scan cycle in response to a determination that said fault has been cleared, and said flag is promptly reset at a conclusion of said second scan cycle.