System and method for implementing time synchronization monitoring and detection in a safety instrumented system

• US 7,489,977 B2
• Filed: 12/19/2006
• Issued: 02/10/2009
• Est. Priority Date: 12/20/2005
• Status: Expired due to Fees

• Current Assignee: Fieldbus Foundation (FieldComm Group, Inc.)
• Original Assignee: Fieldbus Foundation (FieldComm Group, Inc.)
• Inventors: Ramachandran, Ram, Gabler, John Carl, Duffy, Joseph D.
• Primary Examiner(s): DeCady; Albert
• Assistant Examiner(s): Rapp; Chad
• Application Number:
  US11/642,498
• Publication Number:
  US 20070142939A1
• Time in Patent Office: 784 Days
• Field of Search: 700/14, 700/18, 700/78, 700/79
• US Class Current: 700/79
• CPC Class Codes: G06F 1/12 Synchronisation of different clock signals provided by a plurality of clock generators

Abstract

An apparatus, system and process is provided for communicating safety-related data, over an open system, from a sender to a receiver. Safety-related components, including function blocks, flexible function blocks, resource blocks and transducer blocks, as well as, safety-related objects are provided. Also, a time synchronization monitor is provided for monitoring timing distributions and determining when such distributions have drifted beyond an acceptable limit.

Claims

1. An apparatus comprising:

a processor configured to determine whether at least one message communicated over a transmission medium has not been queued by monitoring time synchronization by comparing an actual drift to an allowable drift, wherein the allowable drift is calculated by comparing a first black channel clock determined after processing of a previous time distribution to a second safety layer clock determined after processing of a current time distribution and multiplying the result by a constant; and

a medium attachment unit, which communicates the time distributions and output messages between the processor and a transmission medium.

2. The apparatus of claim 1, further comprising at least one safety-related function block.

3. The apparatus of claim 2, wherein the at least one safety-related function block receives analog input data.

4. The apparatus of claim 2, wherein the at least one safety-related function block is a Safety Instrumented System Function Block.

5. The apparatus of claim 1, further comprising a memory adapted to store at least one non-safety-related function block.

6. The apparatus of claim 1, further comprising a memory configured to store a plurality of function blocks, including a non-safety-related function block and a safety-related function block.

7. The apparatus of claim 6, wherein the non-safety-related function block and the safety-related function block are interconnected to communicate data only from the safety-related function block to the non-safety-related function block.

8. The apparatus of claim 1, wherein the transmission medium includes a digital bus.

9. The apparatus of claim 7, wherein the transmission medium includes a High Speed Ethernet network.

10. The apparatus of claim 1, wherein the processor is adapted for use with at least one of:

a safety-related resource block;

a first safety-related transducer block; and

a second safety-related transducer block.

11. The apparatus of claim 9;

wherein a safety-related resource block insulates a safety-related function block from physical hardware.

12. The apparatus of claim 9, wherein a first safety-related transducer block decouples an input to a safety-related function block, and a second safety-related transducer decouples an output of the safety-related function block.

13. The apparatus of claim 1, wherein the output message is at least Safety Intensity Level-1 compliant.

14. The apparatus of claim 1, wherein the output message is at least Safety Intensity Level-2 compliant.

15. The apparatus of claim 1, wherein the output message is at least Safety Intensity Level-3 compliant.

16. The apparatus of claim 1, wherein the processor generates a virtual protocol data unit prior to communication of the output message.

17. The apparatus of claim 1, wherein the transmission medium further comprises a black channel.

18. The apparatus of claim 1, wherein the transmission medium further comprises a high speed Ethernet.

19. The apparatus of claim 1, further comprising a diagnostic transducer block.