MTBF/MTTR objects are accessed from the Toolbox. (View menu > Toolbox > Add > MTBF MTTR).
MTBF/MTTR objects are used to set random breakdown and recovery times for groups of objects in the model. Each MTBF/MTTR object can have any number of object members and each object can be controlled by more than one MTBF/MTTR object. The MTBF/MTTR object allows you to also specify what state the objects will go into when they go down and what behaviour they should perform. A model may contain any number of MTBF MTTR objects.
Though similar to the Time Table, the MTBF/MTTR object uses picklists to determine dynamically when the connected members will break down and how long they will be broken down for. You can also specify more specific information about the breakdowns. This includes specifying if all connected members will breakdown together, or if the breakdown times will be individually calculated for each object (firing the First Failure Time, Up Time, and Down Time picklists once per object). If you only want the connected members to go down while they are in a specific state, for example a Processor when it is in the processing state, this can be specified as well. This means if the Up Time ends and the Processor is currently idle , then the Processor will not go down until it enters the processing state.
Pages
Name - The name of the MTBF/MTTR. The combobox has a list of all MTBF/MTTR objects in the model, allowing you to quickly jump to different MTBF/MTTR objects.
- Create a new MTBF/MTTR object.
- Delete the current MTBF/MTTR.
- Adds the MTBF/MTTR to a User Library as either a Draggable Icon or an Auto-Install Component.
Apply - Saves all changes to the MTBF/MTTR.
OK - Saves all changes to the MTBF/MTTR and closes the window.
Cancel - Cancels any unsaved changes made to the MTBF/MTTR and closes the window.
Members Page
- This will open an object selection GUI where you can select multiple objects in the model.
- Removes the selected member(s) from the list.
- Reorder's members Up or Down in the list.
- Click to enter "Sample" mode, then click on any object in the model to add it as a member.
Functions Page
The following picklists can be fired individually for each object, or for all the objects together depending on the checked state of Break down members individually from the Breakdowns Page.
First Failure Time - This picklist returns the time of the first failure. Returning a negative number will cause the first failure to be ignored.
Up Time - This function determines how long the objects controlled by this MTBF MTTR object will run before they go into a broken-down state. The Up Time is specifically defined as the span between the time that the object resumes from its last down period and the time that it starts its next down period.
Down Time - This picklist returns the Mean Time To Repair for the objects controlled by this MTBF MTTR object. This function determines how long they will stay in a broken-down state before resuming normal operations again. All of the controlled objects will go back to their original states at the same time.
Down Function - This picklist is executed when the objects in the member list go down. It is executed once for each object in the member list. Here is where you specify what to do to stop the object.
Resume Function - this picklist is executed when the objects in the member list resume their operation. It is executed once for each object in the member list. Here is where you specify what to do to resume the object.
OnBreakDown - This picklist is fired immediately after the Down Function, but it is only executed once, instead of once for each object. See Down/Resume Trigger.
OnRepair - This picklist is fired immediately after the Resume Function, but it is only executed once, instead of once for each object. See Down/Resume Trigger.
Breakdowns Page
Down State - This specifies the state that the object will go into when it goes down.
Break down members individually - If this box is checked, the MTBF/MTTR object will create a separate thread of down and resume events for each member object. If it is not checked, all member objects will go down and resume at the same time.
Apply MTBF to a set of states - This box only applies if the MTBF/MTTR breaks down members individually. If it is checked, then the MTBF time will only be applied to a subset of the object's state. For example, if machine break down data only applies for when the machine is actively processing, then you would use this field. If checked, you will add a set of states to the list on the right from the list of possible states on the left.
Accuracy - This field only applies if the MTBF/MTTR uses a subset of the object's states for its Up Time. Usually this value will be 100, or 100% accuracy. However, if the subset of states represents a very small portion of the total time of the member objects' state times, then the accuracy value can be used to optimize for run speed. For example, if an MTBF is applied to an object's "Waiting for Operator" state, but the object is only in that state 5% of the time, an accuracy value of 100 would cause the MTBF to perform several checks before bringing the object down. If you change the accuracy value to 5, then the MTBF will do much fewer checks before bringing the object down.
Range Cutoff - This field only applies if the MTBF/MTTR uses a subset of the object's states for its Up Time. Usually this value will be 0. However, if the subset of states represents a very small portion of the total time of the member object's state times, then the range cut-off value can be used in conjunction with the accuracy value to improve run speed. This specifies a range within which the MTBF can go ahead and bring the object down. For example, if the next down is scheduled for when the object's subset of states has reached 10000, and the range cutoff is 100, the MTBF will do a check, and if the state subset is above 9900, it will go ahead and bring the object down.
