Dynamic user interrupt scheme in a programmable logic controller
AssigneeSiemens Energy & Automation, Inc.
InventorsRonald Mitchell, Mark Boggs, Robert J. Palermo, Temple Fulton
Life of this patent
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Abstract
The scan cycle in a programmable logic controller is constructed so as to allow the PLC users program to execute an instruction to assign a user program section to which the PLC system is to transfer control upon the occurance of an instruction-specified event. Also allowed is the de-assignment of a user program section from an instruction-specified event. Moreover, the interrupt may happen at any portion of the PLC scan cycle and not merely at compilation time. This thereby allows for dynamically presetting values of characters and the like as well as pipelining of interrupts in the PLC.
Claims9
A dynamic user interrupt scheme in a Programmable Logic Controller (PLC), comprising:
- a PLC having at least one input and one output terminal for transmitting and receiving respectively predetermined signals;
- at least one microprocessor contained in said PLC for executing a user specified plurality of primary calculations and commands, wherein said user specified plurality of primary calculations and commands are performed according to a predetermined cyclical order;
- and
- interrupt means cooperating with said at least one microprocessor for asynchronously interrupting said predetermined cyclical order and stopping said microprocessor from executing said user specified plurality of primary calculations and commands and for performing at least one secondary set of calculations and commands, said interrupt means initiating said interruption in response to a predetermined user specified condition wherein the second set of calculations and commands may be dynamically assigned to said interruption by a program running on the microprocessor.
Dependencies are inferred from the claim text.