Safety controller with hardware memory lock
AssigneeRockwell Automation Technologies, Inc.
InventorsCharles Martin Rischar, Raymond Louis Buvel, Joseph Paul Izzo, Jeremy Stephen Vechinski
Life of this patent
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Abstract
A safety controller provides for reliable mixed execution of standard and safety control programs held in a common memory by providing a hardware lock that is locked at times when the safety program is not executing to minimize potential corruption of the safety program by the standard program.
Claims26
A safety controller comprising:
- a processing unit having a processor executing instructions, and a memory holding instructions and data, the processing unit providing a hardware lock preventing writing of at least a portion of the memory as controllable by a lock instruction, wherein the memory is adapted to hold an independently executing standard program providing control for an industrial process and a safety program and providing control of safety equipment providing human safety in an environment of the industrial process, the safety program requiring higher reliability execution than the standard program;
- and
- a lock management program executable on the processing unit determining when the safety program is to be run and based upon this determination, unlocking a portion of memory holding the safety program at times when the safety program is to run and locking the portion of memory at other times when the safety program is finished running and the standard program is to be run so that the standard program when running cannot corrupt the safety program.
A method of operating a safety controller having a processing unit with a processor executing instructions, and a memory holding instructions and data, the processing unit providing a hardware lock preventing writing of at least a portion of the memory as controllable by a lock instruction, the method comprising the steps of:
- (a) loading a first portion of memory with a standard program providing control for an industrial process and a second portion of memory with a safety program providing control of safety equipment and providing human safety in an environment of the industrial process, the safety program requiring higher reliability execution than the standard program;
- (b) executing the safety program and standard program at different times and determining when the safety program is to be run and based upon this determination, unlocking the second portion of memory at times when the safety program is to run and locking the second portion of memory at other times when the safety program is finished running and the standard program is to be run so that the standard program when running cannot corrupt the safety program.
A method of operating a safety controller system comprising the steps of:
- (a) accepting program instructions from a user describing the logical combination of input sensor data to produce output control data;
- (b) collecting the program instructions into logical tasks;
- (c) identifying the task as to one of two levels of reliability, a first level being of higher reliability than the second level;
- (d) loading a task of the first level into a first portion of memory and a task of the second level into a second portion of memory;
- (e) executing the loaded tasks at different times and determining when the task of the first level is to be run and based upon this determination, unlocking the first portion of memory at times when the task of the first level is executing to run and locking the second portion of memory at other times when the task of the first level is finished running and the task of the second level is to be run so that the task of the second level when running cannot corrupt the task of the first level.
Dependencies are inferred from the claim text.