Equipment fail safe safety system

• US 7,543,170 B2
• Filed: 09/30/2004
• Issued: 06/02/2009
• Est. Priority Date: 09/30/2004
• Status: Expired due to Fees

• Current Assignee: NCC Nano, LLC
• Original Assignee: Novacentrix Corporation
• Inventors: Ross, Rens, McCool, Steven C.
• Primary Examiner(s): Du; Thuan N
• Application Number:
  US10/955,202
• Publication Number:
  US 20060072251A1
• Time in Patent Office: 1,706 Days
• Field of Search: 713/300, 713/340, 714/24, 714/14
• US Class Current: 713/340
• CPC Class Codes: G05B 9/02 electric

Abstract

A system for monitoring and controlling the safety system of equipment, which is used to insure personnel safety and cause the system to “fail safe” in the event of computer or software failure, the failure of a critical piece of hardware, or the opening of any interlock indicating, for example, the unexpected entry of personnel into a dangerous area. Provides an integrated system of timed status monitoring hardware and software for use in a distributed-network computer-controlled environment. The hardware piece of this system includes a digital I/O computer add-on card, or other hardware supporting high-speed alternating state telemetry, and a custom circuit card. Such a circuit, when used within the overall control system can monitor the state of interlock switches and monitor the status of the computer control system(s). Such a safety circuit can then cause a shutdown appropriate to the failure detected. In addition, it has an ability to sense local hardware status information and immediately signal the computer of any potentially dangerous situation.

Claims

1. A safety circuit for monitoring and controlling power to an equipment operated by a computer executing control software to cause said equipment to “

fail safe”

in the event of a safety alert, said safety circuit comprising;

a detector circuit for receiving an alternating state telemetry signal from said computer, wherein said alternating state telemetry signal indicates a satisfactory operation of said computer and said control software;

a relay circuit for applying power to said equipment;

a first counter, coupled to said detector circuit, for outputting a first alert signal to said first relay circuit in response to an interruption in said alternating state telemetry signal received by said detector circuit;

a second counter for outputting a reset signal to cancel said first alert signal in response to a resumption of said alternating state telemetry signal being received by said detector circuit in less than a predetermined timeout period after said interruption, thereby preventing said safety circuit from removing power from said equipment; and

a switching circuit, coupled to said detector circuit, for switching said relay circuit to remove power from said equipment in response to said interruption lasted longer than said predetermined timeout interval.

2. The safety circuit of claim 1, wherein said switching circuit also removes power from said computer when said interruption said interruption lasted longer than said predetermined timeout interval.

3. The safety circuit of claim 1, wherein said safety circuit further includes an interlock circuit for sensing a signal indicative of the status of an interlock and for outputting a second alert signal in response to said interlock circuit sensing said interlock being opened such that said relay circuit, in response to said second alert signal, removes power from said equipment.

4. A safety circuit for monitoring and controlling the power to equipment operated by a computer executing control software to cause said equipment to “

fail safe”

in the event of an alert signal, said safety circuit comprising;

a detector circuit for detecting an alternating state telemetry signal from said computer, wherein said alternating state telemetry signal indicates satisfactory operations of said computer and said control software;

a first counter, coupled to said detector circuit, for outputting an alert signal in response to an interruption in said alternating state telemetry signal received by said detector circuit;

a second counter, coupled to said detector circuit and said first counter, for outputting a reset signal to cancel said alert signal in response to a resumption of said alternating state telemetry signal being received by said detector circuit in less than a predetermined timeout period after said interruption, thereby preventing said safety circuit from removing power from said equipment;

a relay circuit for applying power to the equipment; and

a switching circuit, coupled to said first counter, for receiving said alert signal, wherein said switching circuit is capable of switching said relay circuit to remove power from said equipment in response to said alert signal.