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Automation system with integrated safe and standard control functionality

  • US 7,933,676 B2
  • Filed: 09/30/2005
  • Issued: 04/26/2011
  • Est. Priority Date: 09/30/2005
  • Status: Active Grant
First Claim
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1. An industrial control system, comprising:

  • a machine having a restricted access portion presenting a danger to a human operator in the restricted access portion;

    a machine controller executing a stored control program to;

    a) identify a need for a human operator to be in the restricted access portion wherein the need is based on a planned machine-operator interaction indicated by a point in the control program and not based on detection of a human presence or on an operator input,b) place the machine into a ready state in response to the identification of the need for the operator to be in the restricted access portion by suspending operation of the machine through machine control, andc) upon the control program placing the machine into the ready state, generate a ready message signaling that the control program has identified the machine is in the ready state;

    a protection sensor providing a safety signal, wherein the safety signal implements fault tolerance or fault detection according to the target safety level of the control system, indicating the presence of a human in the restricted access portion; and

    a safety controller, wherein the machine controller and the safety controller are independently functioning computing devices with separate memory for storing variables and programs and each controller independently executes its respective program, the safety controller executing a stored program to;

    a) receive the ready message from the machine,b) receive the safety signal indicating the presence of the human operator in the restricted access portion from the protection sensor,c) after receiving either one of the ready message or the safety signal, initiate placing the machine into a safe state, wherein the safe state suspends operation of at least the restricted portion of the machine by interrupting power to at least the restricted portion of the machine,d) verify that the machine has been placed in the safe state with no fault conditions, ande) if the machine has been placed in the safe state with no fault conditions, provide a human interaction indication sensible by a human that indicates that the machine is ready for human interaction with the restricted access portion in response to receiving the ready message and placing the machine into a safe state;

    whereby the machine is placed in the safe state before the human operator moves into the restricted access portion.

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