Methods and structures for utilizing a memory device for a PLC
AssigneeSiemens Industry, Inc.
InventorsTemple Luke Fulton, Mark Steven Boggs, Steven Michael Hausman, William H. Johnson
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Abstract
Certain exemplary embodiments comprise a method comprising a plurality of activities comprising: at a programmable logic controller comprising a memory device, receiving a request to create a data log that is adapted to receive data from a process; initializing the data log by writing to the data log a head marker code in the record type field of a first record and an invalid code in the record type field of a last record of the data log, the last record logically preceding and logically adjacent to the first record.
Claims13
A method for managing the storage of data, the method comprising:
- at a programmable logic controller comprising a memory device, receiving a request to create a data log comprising a plurality of records, the data log adapted to receive data from a process, each record comprising a record type field;
- initializing the data log by performing the following steps:
- writing, in the record type field of a first record of the data log, a head marker code that indicates that the first record comprises invalid data;
- and
- writing, in the record type field of a last record of the data log, a second code that indicates that the last record comprises invalid data, the second code being different from the head marker code, the last record logically preceding and adjacent to the first record;
- responsive to a determination that the record type code of the first record is indicative of a head marker, automatically invalidating the first record;
- writing a second head marker code in a second record that is logically adjacent the first record and that logically succeeds the first record, the second head marker code indicating that the second record comprises invalid data;
- writing valid data in the first record;
- and
- overwriting the head marker code in the first record with a third code that indicates that the first record comprises valid data.
A machine-readable medium comprising stored machine-executable instructions adapted for:
- at a programmable logic controller comprising a memory device, receiving a request to create a data log comprising a plurality of records, the data log adapted to receive data from a process, each record comprising a record type field;
- initializing the data log by performing the following steps:
- writing, in the record type field of a first record of the data log, a head marker code that indicates that the first record comprises invalid data;
- and
- writing, in the record type field of a last record of the data log, a second code that indicates that the last record comprises invalid data, the second code being different from the head marker code, the last record logically preceding and adjacent to the first record;
- automatically invalidating the first record;
- writing a second head marker code in a second record that is logically adjacent the first record and that logically succeeds the first record, the second head marker code indicating that the second record comprises invalid data;
- writing valid data in the first record;
- and
- overwriting the head marker code in the first record with a third code that indicates that the first record comprises valid data.
Dependencies are inferred from the claim text.