Testing of control strategies in a control system controlling a process control plant

• US 7,844,350 B2
• Filed: 11/22/2006
• Issued: 11/30/2010
• Est. Priority Date: 11/22/2006
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Gnanasekaran, Sathiskumar, Puri, Jagmeet Singh
• Primary Examiner(s): Rodriguez; Paul L
• Assistant Examiner(s): RAO, SHEELA S
• Application Number:
  US11/562,464
• Publication Number:
  US 20080120522A1
• Time in Patent Office: 1,469 Days
• Field of Search: 700 28- 32, 700/39, 702/119, 702/120, 702182-185, 703/6
• US Class Current: 700/30
• CPC Class Codes: G05B 2219/24038 Several test signals stored in memory and used as input signals
• CPC Class Codes: G05B 2219/33286 Test, simulation analysator
• CPC Class Codes: G05B 2219/33324 What to diagnose, whole system, test, simulate
• CPC Class Codes: G05B 23/0208 characterized by the configuration of the monitoring system
• CPC Class Codes: G05B 23/0256 injecting test signals and analyzing monitored process response, e.g. injecting the test signal while interrupting the normal operation of the monitored system; superimposing the test signal onto a control signal during normal operation of the monitored system

Abstract

Test cases to test control strategies of a control process are specified in input files. The instructions in the input files are automatically read by a block tester, which interfaces with the control system to issue the instructions. As a test designer can create the instructions in the input files a priori, the tests may be carefully designed to avoid errors, in addition to performing exhaustive tests.

Claims

1. A method of testing a control strategy in a control system, wherein said control strategy contains a set of functional blocks having a plurality of variables and an output variable, said set of functional blocks being designed to generate output values for said output variable from input values received for said plurality of variables according to a control approach, said method comprising:

receiving from a file a set of input values for a test case, wherein each of said set of input values is specified to be provided for a corresponding one of said plurality of variables,

wherein said receiving further receives from said file an expected output value for said output variable;

providing to said set of functional blocks said set of input values as values corresponding to said plurality of variables, wherein said set of functional blocks generates an actual output value for said output variable according to said control approach;

obtaining said actual output value from said set of functional blocks;

comparing said expected output value with said actual output value to generate a result of said testing of said set of functional blocks for said set of input values of said test case;

wherein said file contains an instruction, wherein said providing sends said instruction to said control system and receives a state of said control strategy in response,

storing said actual output value and said result in said file and said state in a memory,

wherein said file contains a restore instruction; and

retrieving said state from said memory, and loading said state to said control strategy in response to said restore instruction to cause said set of functional blocks to a same state as prior to sending said instruction to said control system;

wherein said receiving receives from said file a wait value associated with said output variable, wherein said obtaining waits a time duration determined by said wait value prior to retrieving said output value for said output variable.

2. The method of claim 1, wherein said receiving receives a first value for a first variable of a first functional block from said file, wherein said first variable is contained in said plurality of variables is set to a CASCADE mode, wherein the input value for said first variable is received as an output value from another functional block in response to setting said first variable to said CASCADE mode, wherein said another functional block is specified by said control strategy, wherein said first functional block and said another functional block are contained in said set of functional blocks.

3. The method of claim 1, wherein said file contains an instruction, wherein said providing sends said instruction to said control system and receives a state of said control strategy in response, said method further comprising storing said state in a memory.

4. The method of claim 3, wherein said file contains a restore instruction, said method further comprising retrieving said state from said memory, and loading said state to said control strategy in response to said restore instruction.

5. The method of claim 4, further comprising:

executing a test case after said storing of said state in said memory,

wherein said test case is also specified in said file,

wherein execution of said test case causes an undesirable condition to occur, and wherein said restore instruction is executed in response to said undesirable condition.

6. The method of claim 1, wherein said file contains a first instruction and a second instruction, said method further comprising setting a second variable of a second control strategy in a database to a corresponding value in response to said first instruction, and loading said second control strategy to said control system in response to said second instruction.

7. The method of claim 1, wherein said result comprises one of pass and fail, wherein said result is set to said pass if said actual output value matches said expected output value and to said fail otherwise.

8. The method of claim 1, further comprising:

receiving from said file an if condition indicating an instruction to be executed if said if condition is evaluated to be true and not to be executed otherwise, wherein said if condition specifies a comparison of a value received set of functional blocks for said set of functional blocks with a desired value;

evaluating said condition by comparing said actual output value obtained from said set of functional blocks with said desired value received from said file to determine whether said condition evaluates to true; and

executing said instruction only if said condition is evaluated to be true and not executing said instruction otherwise.

9. A computer readable medium carrying one or more sequences of execution statements for causing a system to test a control strategy in a control system, wherein said control strategy contains a set of functional blocks having a plurality of variables and an output variable, said set of functional blocks being designed to generate output values for said output variable from input values received for said plurality of variables according to a control approach, wherein execution of said one or more sequences of execution statements by one or more processors contained in said system causes said system to perform the actions of:

receiving from a file a set of input values for a test case, wherein each of said set of input values is specified to be provided for a corresponding one of said plurality of variables,

wherein said receiving further receives from said file an expected output value for said output variable;

providing to said set of functional blocks said set of input values as values corresponding to said plurality of variables, wherein said set of functional blocks generates an actual output value for said output variable according to said control approach;

obtaining said actual output value from said set of functional blocks;

comparing said expected output value with said actual output value to generate a result of said testing of said set of functional blocks for said set of input values of said test case;

wherein said file contains an instruction, wherein said providing sends said instruction to said control system and receives a state of said control strategy in response,

storing said state in a memory and said actual output value and said result in said file; and

wherein said file contains a restore instruction,

retrieving said state from said memory, and loading said state to said control strategy in response to said restore instruction to cause said set of functional blocks to a same state as prior to sending said instruction to said control system; and

wherein said receiving receives from said file a wait value associated with said output variable, wherein said obtaining waits a time duration determined by said wait value prior to retrieving said output value for said output variable.

10. The computer readable medium of claim 9, wherein said receiving receives a first value for a first variable of a first functional block from said file, wherein said first variable is contained in said plurality of variables is set to a CASCADE mode, wherein the input value for said first variable is received as an output value from another functional block in response to setting said first variable to said CASCADE mode, wherein said another functional block is specified by said control strategy, wherein said first functional block and said another functional block are contained in said set of functional blocks.

11. The computer readable medium of claim 9, wherein said contains a first instruction and a second instruction, further comprising one or more execution statements for setting a second variable of a second control strategy in a database to a corresponding value in response to said first instruction, and loading said second control strategy to said control system in response to said second instruction.

12. The computer readable medium of claim 9, wherein said result comprises one of pass and fail, wherein said result is set to said pass if said actual output value matches said expected output value and to said fail otherwise.

13. The computer readable medium of claim 9, further comprising:

executing a test case after said storing of said state in said memory,

wherein said test case is also specified in said file,

wherein execution of said test case causes an undesirable condition to occur, and wherein said restore instruction is executed in response to said undesirable condition.

14. The computer readable medium of claim 9, further comprising:

receiving from said file an if condition indicating an instruction to be executed if said if condition is evaluated to be true and not to be executed otherwise, wherein said if condition specifies a comparison of a value received set of functional blocks for said set of functional blocks with a desired value;

evaluating said condition by comparing said actual output value obtained from said set of functional blocks with said desired value received from said file to determine whether said condition evaluates to true; and

executing said instruction only if said condition is evaluated to be true and not executing said instruction otherwise.

15. An apparatus for testing a control strategy in a control system, wherein said control strategy contains a set of functional blocks having a plurality of variables and an output variable, said set of functional blocks being designed to generate output values for said output variable from input values received for said plurality of variables according to a control approach, said apparatus comprising:

means for receiving from a file a set of input values for a test case, wherein each of said set of input values is specified to be provided for a corresponding one of said plurality of variables,

wherein said means for receiving further receives from said file an expected output value for said output variable;

means for providing to said set of functional blocks said set of input values as values corresponding to said plurality of variables, wherein said set of functional blocks generates an actual output value for said output variable according to said control approach

means for obtaining said actual output value from said set of functional blocks;

means for comparing said expected output value with said actual output value to generate a result of said testing of said set of functional blocks for said set of input values of said test case;

means for storing said actual output value and said result in said file,

wherein said file specifies a save checkpoint instruction, wherein said providing sends said save checkpoint instruction to said control system and receives a state of said set of functional blocks in response, means for storing said state in a non-volatile memory upon receipt of said state; and

wherein said file further contains a restore instruction after said save checkpoint instruction, at least one another intermediate instruction being contained between said save checkpoint instruction and said restore instruction;

means for retrieving said state from said non-volatile memory, and loading said state to said control strategy in response to said restore instruction to cause said set of functional blocks to be restored to a state just prior to sending of said save checkpoint instruction; and

means for executing said at least one another intermediate instruction between said restore instruction and said save checkpoint instruction,

wherein said means for receiving is operable to receive from said file a wait value associated with said output variable, wherein said means for obtaining is operable to wait a time duration determined by said wait value prior to retrieving said output value for said output variable.

16. The apparatus of claim 15, wherein said result comprises one of pass and fail, wherein said result is set to said pass if said actual output value matches said expected output value and to said fail otherwise.

17. The apparatus of claim 15, further comprising:

means for receiving from said file an if condition indicating an instruction to be executed if said if condition is evaluated to be true and not to be executed otherwise, wherein said if condition specifies a comparison of a value received set of functional blocks for said set of functional blocks with a desired value;

means for evaluating said condition by comparing said actual output value obtained from said set of functional blocks with said desired value received from said file to determine whether said condition evaluates to true; and

means for executing said instruction only if said condition is evaluated to be true and not executing said instruction otherwise.