Step Execution

Depending on the options you specify when you configure a step, a step performs multiple actions as it executes. The following table lists the most common actions a step can take, in the order the step performs them.

Action Number Description Remarks
1 Allocate step result —
2 Enter batch synchronization section When option is set
3 Check run mode for Skip Sets the corresponding status on the step, then proceeds to Action Number 34
4 Evaluate precondition When False, performs Action Number 29, then proceeds to Action Number 33
5 Acquire step lock When option is set
6 Check run mode for Force Pass or Force Fail Sets the corresponding status on the step, then proceeds to Action Number 30
7 Load module if not already loaded —
8 Execute step switching —
9 Evaluate Loop Initialization expression Only when looping
10 Evaluate Loop While expression, skip to Action Number 27 when False Only when looping
11 Allocate loop iteration result Only when looping
12 Call Pre-Step Engine callbacks —
13 Evaluate Pre-Expression —
14 Call Pre-Step substeps for step type —
15 Process additional results for input parameters —
16 Call module —
17 Process additional results for output parameters —
18 Call Post-Step substeps for step type TestStand calls Post-Step substeps even when the user code module generates a run-time error, which enables Post-Step substeps to perform error handling, when appropriate. If Post-Step substeps clear run-time errors, proceed to Action Number 19. If step is configured to ignore run-time errors, proceed to Action Number 23.
19 Evaluate Post-Expression —
20 Evaluate Status expression —
21 Call Post-Step Engine callbacks —
22 Call Post-Step Failure Engine callback Only when loop iteration fails
23 Populate loop iteration result Only when looping
24 Call Post-ResultList Entry Engine callback Only when looping
25 Call Post-Results Engine callback Only when looping
26 Evaluate Loop Increment expression, return to Action Number 10 Only when looping
27 Evaluate Loop Status expression Only when looping
28 Disconnect switching routes with step lifetime —
29 Unload module when required —
30 Update sequence failed state —
31 Call Post-Step Failure Engine callback Only when step fails
32 Execute post action —
33 Release step lock When option is set
34 Exit batch synchronization section When option is set
35 Populate step result Custom additional results also populate at this time. However, additional results for input and output parameters populate immediately before and after Action Number 16, respectively.
36 Call Post-ResultList Entry Engine callback —
37 Call Post-Results Engine callback —

Usually, a step performs only a subset of these actions depending on the configuration of the step and the test station. When TestStand detects a run-time error in one of these actions, it calls the Post-Step Error Engine callbacks. When you do not define these callbacks or when the callbacks do not reset the error state for the step, TestStand executes the following actions to clean up the execution of the step:

  • If the error occurs before the step calls the code module, TestStand does not call the code module and proceeds to Action Number 28.
  • If the error occurs while the step is calling the code module, TestStand proceeds to Action Number 28.
  • If the error occurs after the step calls the code module, TestStand calls Action Number 21, if it is not already called, and proceeds to Action Number 28.
  • If a run-time error occurs in a loop iteration, TestStand also populates the loop iteration result, Action Number 23.