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US 7,213,168 B2Granted
Safety controller providing for execution of standard and safety control programs
AssigneeRockwell Automation Technologies, Inc.
InventorsMichael Dean Kalan, Charles Martin Rischar
Life of this patent
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Abstract
A safety controller may execute both standard and safety programs using shared architecture in which two processors symmetrically execute the safety program and check each other for errors, and one processor only executes the standard program to minimize undetected symmetrical corruption of the safety programs.
Claims27
A safety controller comprising:
- a primary processing unit having a first processor communicating with a first memory holding a safety program requiring a first reliability of operation and a standard program requiring a second reliability of operation less than the first reliability of operation;
- a second processing unit having a second processor independent from the primary processing unit and communicating with a second memory independent from the first memory and holding the safety program and not the standard program;
- and
- a synchronization program executable by the primary and partner processing units to execute the standard program in the primary processing unit only and to execute the safety program in the primary and second processing units and to compare execution of the safety programs to enter a safety state when this execution differs;
- wherein the safety program and the standard program execute to generate outputs to be used to control an external device and wherein the synchronization program compares execution of the safety program by comparing outputs generated by the primary and second processing units' execution of the safety program;
- and
- wherein the safety program is executed repeatedly and wherein the synchronization program compares execution of the safety program at each repeated execution prior to outputting of the output values generated by the safety program to the external device.
4 more elements
A safety controller system comprising:
- a programming tenmnal executing a programming tool to:
- (a) accept program instructions from a user describing a logical combination of input sensor data to produce output control data;
- (b) collect the program instructions into tasks;
- (c) identify the tasks as to one of a first and second level of reliability, the first level executable on a single processing unit only and the second level requiring execution in tandem on two processing units having an ability to compare execution to determine a fault in either of the two processors and to then enter a safety state;
- and
- a safety controller having at least two independent processing units executing a stored program to receive the tasks from the programming terminal and provide both the first and second processing units with tasks identified to the second level and provide the first processing unit only the tasks identified to the first level.
3 more elements
A safety controller kit comprising:
- a first controller having a first housing attachable to a backplane to communicate with other components of a control system, the first controller accepting control programs requiring a first level of reliability;
- a second controller having a second housing attachable to the backplane to communicate with the first controller, the second controller accepting control programs requiring a second level of reliability greater than the first level of reliability to execute the control programs in tandem with the first controller;
- and
- wherein the first controller further only accepts programs of the second level of reliability when the second controller is in communication with the first controller over the backplane.
1 more element
A method of operating a safety controller having primary and partner independent processing units comprising the steps of:
- (a) receiving a safety program requiring a second reliability of operation and a standard program requiring a first reliability of operation less than the second reliability of operation;
- (b) loading the safety program in the primary and partner processing units and executing the safety program in tandem in the primary and partner processing unit to enter a safety state when execution differs in the primary and partner processing units;
- and
- (c) loading the standard program in the primary processing unit only and executing the standard program;
- wherein step (a) receives the standard program and the safety program at the primary processing unit only and transfers the safety program only to the partner processing unit;
- and
- wherein the safety program holds an identification value indicating that it is a safety program and step (a) identifies the safety program to be transferred by the identification value.
4 more elements
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 executable on a single processor and a second level requiring execution in tandem on two processors having an ability to compare execution to determine a fault in either of the two processors and to then enter a safety state;
- (d) executing the tasks identified to the first level of reliability on a first processor only;
- and
- (e) execution of the task identified to the second level of reliability on the first and a second processor in tandem to identify processor faults.
3 more elements
Dependencies are inferred from the claim text.