Error while using operators for breakdown

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Manoj K5 asked Dec 14, '21 Jeanette F commented Dec 22, '21

Error while using operators for breakdown

I am facing problem with MTBF MTTR.

case1) I am using operators for repair and is given under Stop objects and call operators in Down function. I haven't selected any states from Apply MTBF to set of states in Breakdowns tab. The total breakdown after model run is coming around 16.52 percent.

case 2) For the same model, I ran with all the states included in Breakdowns tab and now the breakdown reduced to 16.14 percent.

case 3 & 4) I also ran the model without operators with and without the states included. I am getting the breakdown as 16.52.

The problem is clearly with the case 2 which I am not able to rectify (while using operators with MTBF lists activated). (Attached the screenshot with states for MTBF selected).

Also attached the Model for reference.

Kindly resolve the problem.

Thanks.

Software Version:

FlexSim 19.1.2

mtbfmttr interface

1639581504300.png (33.8 KiB)

failure-mtbf-list-testing.fsm (37.3 KiB)

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Jeanette F ♦♦ commented · Dec 22, 2021 at 04:22 PM

Hi @Manoj K5, was Phil BoBo's answer helpful? If so, please click the "Accept" button at the bottom of their answer. Or if you still have questions, add a comment and we'll continue the conversation.

If we haven't heard back from you within 3 business days we'll auto-accept an answer, but you can always unaccept and comment back to reopen your question.

0 ·

Answer 1 · 2021-12-17T21:27:15Z

Phil BoBo answered Dec 17, '21 Phil BoBo edited Dec 17, '21

This is a problem with the order of events in the picklist option "Stop Object and Call Operators".

The problem is that the MTBF_MTTR_FINISH_DOWN_TIME_NO_RESUME message is happening after the TASKTYPE_STOPREQUESTFINISH task that changes the state.

When using "Apply MTBF to a set of states", the MTBFMTTR object listens to the state change of the object to determine when to fire the triggers. Since the state change (in TASKTYPE_STOPREQUESTFINISH) is happening before the event in MTBF_MTTR_FINISH_DOWN_TIME_NO_RESUME, the next down event is not being scheduled until the next state change of the processor when it finishes processing the current item.

You can fix it by simply changing the order of lines 50 and 51 in the code so that the TASKTYPE_SENDMESSAGE comes before the TASKTYPE_STOPREQUESTFINISH.

1639776476096.png (155.0 KiB)

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