Methods and apparatus for maintaining a programmable logic control revision history
AssigneeGE Fanuc Automation North America, Inc.
InventorsWilliam M. Huntley, Stephen A. Hogge
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Abstract
Methods and apparatus for maintaining a PLC revision history are described. In one embodiment, the PLC creates and maintains a revision history log that provides information related to changes made to the PLC user program and/or the PLC configuration. If a change is detected, information regarding the change is gathered and stored in the history log. The history log maintains a record of the revisions made to the PLC. If the history log becomes full, the oldest revision entry is deleted and the latest change is incorporated into the history log.
Claims17
A method for maintaining and updating a revision history in a programmable logic controller (PLC), the PLC having a central processing unit, a memory including a user program stored therein, and a hardware configuration including at least one input/output (I/O) module, said method comprising the steps of:
- creating a history log in the PLC memory by:
- accessing the PLC memory;
- and
- opening the history log, the history log comprising a plurality of entries,
- wherein each entry comprises the time of change and type of change;
- detecting whether a change is being made to at least one of the user program stored in the PLC memory and the PLC hardware configuration;
- and
- if a change is detected, then selectively placing an entry in the history log.
A system for maintaining a revision history, said system comprising a central processing unit, a memory, a user program stored in the memory, and a hardware configuration comprising at least one I/O module, said system configured to:
- create a history log in the memory by:
- accessing the memory;
- and
- opening the history log, wherein the history log comprises at least one entry that comprises the time of change and type of change;
- detect whether a change is being made in at least one of the user program stored in the memory and the system hardware configuration;
- and
- if a change is detected, then selectively place an entry into the history log.
Dependencies are inferred from the claim text.