Implementing a multitest POU

In the declaration part of the test POU, declare an instance of the testee. The example tests a CTU standard POU.

{attribute 'test':='multitest'}
{attribute 'testcasetimeout':='15000'}
FUNCTION_BLOCK CTU_TestCases EXTENDS TM.BaseMultiTest
VAR_INPUT
END_VAR
VAR_OUTPUT
END_VAR
VAR
	counter : CTU;	// testee instance
	cycleCounter : INT; // independant test control variable
END_VAR

In the implementation part of the prvStart method, initialize the testee. The example initializes the CTU via reset and, if necessary, initializes variables which are required for the test flow. The prvStart method is called one time before prvCyclicAction.

SUPER^.prvStart();  // mandatory - don't change

// Initialize the testee
counter(CU:=FALSE, RESET:=TRUE);	// reset the counter; note: initialization per test case must be performed in prvCyclicAction

// Initialize test control variable for first test case
cycleCounter := 0;

Call the testee and check its result in the prvCyclicActionmethod. The prvCyclicAction method is called until xDone is set to TRUE. As a result, the testee can be called over multiple PLC cycles for each test case. The following example implements only one test case (CASE 0), but other test cases can easily be added according to this scheme.

SUPER^.prvCyclicAction();   // mandatory - dont' change
 
CASE diTestCaseIndex OF
    0:	// test case #0; add test cases as new CASEs
        IF xGetTestInfo THEN    // initializate test case
            //  define mandatory test case information
            wsTestCaseName := "Count from 0 to 5";
            wsTestCaseCategories := "CTU";
            diTestCaseTimeout := 500;
             
            xDone := TRUE;  // signal test case initialization done
        ELSE
			IF (cycleCounter = 0) THEN
				// prepare test case
				counter(CU:=FALSE, RESET:=TRUE, PV:=5);	
	
			// stimulate testee as long as we expect: 5 rising edges to count to 5 equals minimum 10 cycles
			ELSIF (cycleCounter < 10) THEN 
				// check: counter limit not reached yet
				TM.Assert_Bool_IsFalse(THIS^, counter.Q, "Counter signaled limit reached prematurely");
				TM.Assert_Word_Less(THIS^, 5, counter.CV, "Counter reached limit unexpectedly");	
			
				counter(CU:= (NOT counter.CU), RESET:=FALSE);	// Trigger counter with rising edges
				
				xDone := FALSE;   // signal test still running
			ELSE
				// check: counter reached limit
				TM.Assert_Bool_IsTrue(THIS^, counter.Q, "Counter did not signal limit reached");
				TM.Assert_Word_Equal(THIS^, 5, counter.CV, "Counter did not reach limit");
				 
				xDone := TRUE;    // mandatory: signal test completed
			END_IF
			
			IF xDone OR xError THEN
				cycleCounter := 0;	// clean up for next test case
			ELSE
				cycleCounter := cycleCounter + 1;	// count cycles	
			END_IF
        END_IF
    ELSE
        IF diTestCaseIndex < 0 THEN  // mandatory, signal number of test cases, if called with (diTestCaseIndex < 0)
            diTestCaseCount := 1;
            xDone := TRUE;
        ELSE    // mandatory, don't remove: fail for invalid test case index
            wsInfo := "Invalid test case index";
            iError := 2;
        END_IF
END_CASE

Uninitialization of the test could be done in the prvResetOutputs method, but it is not necessary in this example. Delete the method.

No special code needs to be executed if the test times out. Delete the prvAbort method.