Method of maintaining a data log related to a Programmable Logic Controller (PLC)

• US 7,793,056 B2
• Filed: 09/04/2007
• Issued: 09/07/2010
• Est. Priority Date: 12/23/2002
• Status: Active Grant

• Current Assignee: Siemens Industry Incorporated (Siemens AG)
• Original Assignee: Siemens Industry Incorporated (Siemens AG)
• Inventors: Hausman, Steven Michael, Fulton, Temple Luke, Johnson, William H., Boggs, Mark Steven
• Primary Examiner(s): CHOE, YONG J
• Application Number:
  US11/899,115
• Publication Number:
  US 20070300021A1
• Time in Patent Office: 1,099 Days
• Field of Search: 711/154, 711/100, 711/115, 711/161, 714/15
• US Class Current: 711/154
• CPC Class Codes: G05B 19/05 Programmable logic controllers, e.g. simulating logic interconnections of signals according to ladder diagrams or function charts
• CPC Class Codes: G05B 2219/13161 Easily exchangable rom, eprom cassette, earom
• CPC Class Codes: G05B 2219/13171 Portable, detachable programming unit

Abstract

Certain exemplary embodiments can provide a method for utilizing a memory cartridge connected to a Programmable Logic Controller (PLC). The memory cartridge can comprise a plurality of memory segments. The method can comprise a plurality of activities comprising: providing a default identifying stamp for records in a data log file, a structure for the data log file stored separately from the data log file in the memory cartridge, and obtaining a request to provide the data log file.

Claims

1. A method for utilizing a memory cartridge connected to a programmable logic controller (PLC), the memory cartridge comprising a plurality of memory segments, the method comprising a plurality of activities comprising:

locating, on the memory cartridge, a first head marker relatable to a first data log record, the first head marker indicative of a beginning memory segment for a second data log record to be written; and

writing the second data log record to at least the beginning memory segment, the second data log record corresponding to a data log file structure stored separately from a corresponding data log file on the memory cartridge, the data log file structure structurally defining the data log file and comprising a symbolic representation of how the data log file is formatted for storage and retrieval, the data log file structure stored as part of a projectile, the project file further comprising a PLC program and a recipe structure.

2. The method of claim 1, wherein the second data log record comprises a second head marker.

3. The method of claim 1, wherein said writing activity causes a second head marker to be created relatable to the second data log record.

4. The method of claim 1, further comprising:

changing the first head marker to be a non-head marker.

5. The method of claim 1, further comprising:

reading the second data log record.

6. The method of claim 1, further comprising:

responsive to a power failure, determining that two head markers in the data log file are turned on simultaneously.

7. The method of claim 1, further comprising:

responsive to a power failure, via an error checking technique, identifying which of two records comprising a head marker is most recent in the data log file.

8. The method of claim 1, further comprising:

responsive to a power failure, via a Fletcher checksum method, identifying which of two records comprising a head marker is most recent in the data log file.

9. The method of claim 1, further comprising:

responsive to a power failure, via an extended-precision checksum method, identifying which of two records comprising a head marker is most recent in the data log file.

10. The method of claim 1, further comprising:

responsive to a power failure, converting a duplicate head marker to a non-head marker in the data log file.

11. The method of claim 1, further comprising:

responsive to a power failure, changing a value of a binary bit to disable a duplicate head marker in the data log file.

12. The method of claim 1, further comprising:

responsive to a power failure, inspecting a time stamp marker to determine a most recently written record in the data log file.

13. The method of claim 1, further comprising:

responsive to a received user input of an option to erase a read data log file, automatically erasing the data log file from the memory cartridge.

14. The method of claim 1, further comprising:

responsive to a received user input of an option to erase a read data log file, automatically erasing the data log file from the memory cartridge, the user input received responsive to a prompt, a beginning memory segment the data log file identified via a record marker, a last written record of the data log file identified via a second head marker associated with the second data log record.

15. The method of claim 1, further comprising:

receiving a user input regarding an option to erase the data log file, the PLC adapted to erase the data log file responsive to the user input after the data log file is read.

16. The method of claim 1, wherein the data log file is written in a logically circular buffer, the PLC adapted to write a next data log record at a beginning of the logically circular buffer when the logically circular buffer is full.

17. The method of claim 1, wherein the second data log record overwrites a memory segment used by an older data log record.

18. A method comprising a plurality of activities comprising:

on a memory cartridge connected to a programmable logic controller (PLC), writing a first data log record to at least a beginning memory segment of the memory cartridge, the memory cartridge comprising a plurality of memory segments, the first data log record corresponding to a data log file structure stored separately from a data log file on the memory cartridge, the data log file structure structurally defining the data log file and comprising a symbolic representation of how the data log file is formatted for storage and retrieval, the data log file structure stored as part of a project file, the project file further comprising a PLC program and a recipe structure, the beginning memory segment located via a first head marker relatable to a second data log record, the first head marker indicative of the beginning memory segment.

19. A machine-readable medium comprising computer-executable instructions for activities comprising:

locating, on a memory cartridge connected to a programmable logic controller (PLC), a first head marker relatable to a first data log record, the first head marker indicative of a beginning memory segment for a second data log record to be written, the memory cartridge comprising a plurality of memory segments;

writing the second data log record to at least the beginning memory segment, the second data log record corresponding to a data log file structure stored separately from a corresponding data log file on the memory cartridge, the data log file structure structurally defining the data log file and comprising a symbolic representation of how the data log file is formatted for storage and retrieval, the data log file structure stored as part of a project file, the project file further comprising a PLC program and a recipe structure;

creating a second head marker relatable to the second data log record; and

changing the first head marker to be a non-head marker.