Monitor system
First Claim
1. A monitor system for monitoring a microprocessor based control device having an output for effecting control of a system by means of control information therefrom in dependence on reference information received from system sensors of physical parameters in safety critical situations, said monitor system being configured without the requirement of a further microprocessor and including first input means for receiving said control information from the output of the microprocessor based control device;
- second input means for receiving reference information from the system sensors;
memory means having address inputs continuously receiving both the control information and the reference information form the first and second input means respectively to define in combination an accessed memory address wherein the contents of said accessed memory address is used for continuously determining whether the control information from the device corresponds to that expected in view of the reference information; and
means for overriding the control information if any error in this control information is detected.
4 Assignments
0 Petitions
Accused Products
Abstract
A monitor system for safety critical situations such as burner control receives at inputs 17-21 control information from a programmable logic control and reference information at inputs 12-16 from plant interlocks. This information passes via opto-isolators 40 and buffers 41 to the address bus of an EPROM so as to access information stored therein which normally mirrors the PLC information so as to control relays RL1-5 via drivers 45 to conform to the PLC instructions. The EPROM also contains reset and clock information for use by a counter 48 which allows different areas within the EPROM to be accessed. The reset information is also available to a parity check circuit 49 via oscillator 46 for dynamically testing the monitor for integrity of operation. Failure of the PLC or monitor components will cause access to shutdown addresses of the EPROM and operation of the appropriate relays including lockout relay RL6.
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Citations
30 Claims
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1. A monitor system for monitoring a microprocessor based control device having an output for effecting control of a system by means of control information therefrom in dependence on reference information received from system sensors of physical parameters in safety critical situations, said monitor system being configured without the requirement of a further microprocessor and including first input means for receiving said control information from the output of the microprocessor based control device;
- second input means for receiving reference information from the system sensors;
memory means having address inputs continuously receiving both the control information and the reference information form the first and second input means respectively to define in combination an accessed memory address wherein the contents of said accessed memory address is used for continuously determining whether the control information from the device corresponds to that expected in view of the reference information; and
means for overriding the control information if any error in this control information is detected. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
- second input means for receiving reference information from the system sensors;
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19. A monitor for independently monitoring a microprocessor based control device provided to control a system in safety critical situations, said microprocessor based control device having an input for receiving reference information from system sensors of physical parameters and an output for supplying control information to said system in dependence on said reference information from said system sensors, said monitor including first input means for receiving the control information for the system control from the microprocessor based control device;
- second input means for receiving the reference information from the system sensors, memory means for continuously receiving both the system control information and the reference information from the first and second input means respectively, and generator means connected to an input of said memory means for generating addresses to define an accessible memory address in combination with the control information and the reference information wherein the contents of said address memory is used for continuously determining whether the control information from the said device corresponds to that expected in view of the reference information; and
means for overriding the control information for the system control if any error in this control information is detected. - View Dependent Claims (20, 21, 22, 23, 24, 25)
- second input means for receiving the reference information from the system sensors, memory means for continuously receiving both the system control information and the reference information from the first and second input means respectively, and generator means connected to an input of said memory means for generating addresses to define an accessible memory address in combination with the control information and the reference information wherein the contents of said address memory is used for continuously determining whether the control information from the said device corresponds to that expected in view of the reference information; and
- 26. In a burner system having a plurality of sensors for providing reference information indicative of the status of the burner system and a microprocessor based control device for receiving reference information, said device including an output for providing control information to control burner operation in dependence on the reference information, the improvement comprising a monitor device having first input means for receiving the control information controlling burner operation, second input means for receiving the reference information indicative of burner status, memory means for continuously receiving both the control information and the reference information for the purpose of selecting memory addresses within said memory means for measuring physical parameters from the first and second input means respectively and wherein the control units of said selected address within said memory means is used for continuously determining whether the control information from said control device corresponds to that expected in view of the reference information, means for overriding the control information if any error in this control information is detected and means for checking the integrity of the memory means to ensure correct operation thereof is effected, said means for checking the integrity of the memory means including feedback means connected between an output of the memory means and an input thereto, said memory input being configured to receive addressing information dependent on information stored within the memory means together with the control information and reference information from the first and second input means to define an accessed memory address.
Specification