The Downtime block defines either maintenance, repairs, or any other type of activity that is different from the usual activity of specific markup elements (cranes, conveyors, conveyor stations), resources defined by the ResourcePool block or transporters defined by the TransporterFleet block.
You can schedule the recurring downtime activities either by using different types of triggers or by using the Schedule element. You can also customize the time of the first occurrence for this activity.
If you define multiple first occurrence triggers, the first one to fire will start the countdown for the triggers that define the recurrence period for this activity, if you have specified them.
If you do not define any triggers for the first occurrence and only specify the recurrence interval, the first occurrence will occur when the specified interval has elapsed. For example, if you define a cycle of 50 work hours, the first downtime will occur when the resource has accumulated 50 work hours from the start of the model run and will repeat at the same frequency until you stop the simulation.
A set of resources may have multiple tasks with different priorities and preemption policies.
- If all tasks have the same priority, they will be executed in the usual way following their occurrence schedule. If there are enough resource units available, tasks can be executed simultaneously. If two tasks have the same priority, but one of them was suspended for some reason, this suspended task will be picked1.
- If you have configured no preemption policy for the tasks, these tasks will be executed one after another following their occurrence schedule. If there are enough resource units available, tasks can be executed simultaneously.
- The occurrence of one task does not reset the priorities for other tasks.
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The suspended tasks from the individual queue of the resource unit have the highest priority.
This queue is formed by agents waiting in blocks that have the Task preemption policy set to Wait for original resource. -
After that, the suspended tasks from the queue of the ResourcePool block are processed.
This queue is formed by agents waiting in the blocks that have the Task preemption policy set to Seize any resource.
Once the suspended tasks from these queues are completed, the resource unit begins to process new tasks from their individual queues, and after that, the queue of the ResourcePool block.
If this order does not suit your needs, manually decrease the task’s priority by code, using the On task suspended action of the block.
If a downtime task is scheduled — whether as a maintenance task or a custom task — and at the scheduled start time the resource is still engaged in a higher-priority task, the downtime task will be delayed until the resource completes the higher-priority task.
Suppose we have a downtime maintenance task specified with an “on”-“off” schedule. The “on” interval defines the maintenance task and is set to 2 hours long. It repeats every 10 hours, so the “off” interval is 8 hours. If a higher priority task takes up the first hour of the scheduled “on” interval, then the maintenance task will start at the second hour and last for the scheduled 2 hours. The “off” interval will decrease by the same amount of time that the higher priority task has taken up from the scheduled interval, and will last for 7 hours instead of 8.
The downtime tasks of a particular ResourcePool block may occur at the same time as the end of the shift specified by the properties of that block. In this case, these downtime tasks are moved to the event queue of that ResourcePool. They will start when the end of shift task is completed, that is, when the next shift starts.
During downtime, resources, transporters, and cranes can return to their designated home location or another specified location. Select returns home or goes to… in the At downtime equipment field to specify where to send the equipment during downtime.
The specifics of how the Downtime block works for markup elements are covered in the articles that describe those elements (in the Maintenance, failures, breaks section of their properties).
Demo model: Maintenance of a Coffee Machine Open the model page in AnyLogic Cloud. There you can run the model or download it (by clicking Model source files). Demo model: Maintenance of a Coffee MachineOpen the model in your AnyLogic desktop installation.- The type of the element that goes into downtime. In this article, it is referred as T. Has the following options:
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General — The default state, which causes the Downtime block to affect both agents and markup elements.
- Conveyor — The Downtime block affects conveyors.
- Station — The Downtime block affects conveyor stations.
- Jib Crane — The Downtime block affects jib cranes.
- Overhead Crane — The Downtime block affects bridges on an overhead crane.
You can also choose an agent type from the list; however, only transporters and resources are compatible with the downtime block.
If this Downtime block is used in your model only by resources or equipment of some specific type, you can choose here the corresponding option. It will simplify accessing units in other parameters and functions of this block: unit local variable will have the type defined here and you will be able to access any custom fields of equipment or resource units without type casting. However, if you plan to use this block for units of different types, you should leave the default General option, and cast unit variable to actual type if required.
If one type is selected as the Unit type (for example, Conveyor) and the Downtime block is used to model downtime for another type (for example, a Jib crane), an error will occur.
Default value: IMaintenanceable
Valid values:IMaintenanceable — General
ConveyorPath — Conveyor
ConveyorSimpleStation — Station
JibCrane — Jib Crane
OverheadCraneBridge — Overhead Crane
Agent — Agent
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- Type
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The type of downtime task performed by the resource units. The available options are Maintenance (may be triggered by schedule), Failure / repair (may not be triggered by schedule) or Custom (any type of interrupting activity for resource units).
Syntax: Downtime.ActivityType activityType
Valid values:
Downtime.ACTIVITY_MAINTENANCE — Maintenance
Downtime.ACTIVITY_FAILURE — Failure / repair
Downtime.ACTIVITY_CUSTOM — Custom -
[Visible and applies only if the Type is defined as either Maintenance or Custom]
Here you can choose whether you want to schedule tasks by defining the Triggers or you prefer to use AnyLogic Schedule instead.Value type: DowntimeDescriptor.TriggerType -
[Visible if the Defined by parameter is set to Schedule]
The schedule defining the occurrence pattern for the task. The schedule should be set to the “on/off” mode. During the “on” periods, the resource is on downtime. -
[Visible if the Defined by parameter is set to Triggers]
Here you can specify the period of working time (when the resource unit services an agent) and idle time that must pass between the assignments of this task. If the field is left empty, this type of trigger will not be applied. -
[Visible if the Defined by parameter is set to Triggers]
Here you can specify when the countdown for the Total time between occurrences parameter must start: either when the task starts or when the task finishes. If the downtime task has been started by a different trigger, the Total time between occurrences countdown will be restarted after the downtime task finishes.Value type: boolean -
[Visible if the Defined by parameter is set to Triggers]
Here you can specify the period of working time that must pass between the assignments of this task. Working time includes the time spent by the resource to reach the agent that seized it and the time of service itself. If the field is left empty, this type of trigger will not be applied. -
[Visible if the Defined by parameter is set to Triggers]
The number of times this resource must be seized between the assignments of this task. If the resource work was interrupted after it had been seized but then resumed once again, this is counted as two cycles. If the field is left empty, this type of trigger will not be applied. -
[Visible if the Defined by parameter is set to Triggers]
Enables the custom trigger values for the first downtime occurrence. If not enabled, the first downtime will occur when the recurrence period specified for the repeating downtime task runs out. -
[Visible if the Custom first occurrence option is selected]
Here you can specify the amount of time that must pass from the appearance of the resource unit until this task is first assigned to the resource. It includes both working time (when the resource unit services an agent) and idle time. If the field is left empty, this type of trigger will not be applied. -
[Visible if the Custom first occurrence option is selected]
Here you can specify the amount of working time that must pass until this task is first assigned to the resource. Working time includes the time spent by the resource to reach the agent that seized it and the time of service itself. If the field is left empty, this type of trigger will not be applied. -
[Visible if the Custom first occurrence option is selected]
The number of times this resource has been seized until this task is first assigned to the resource. If the resource work was interrupted after it had been seized and then resumed once again, it is counted as two cycles. If the field is left empty, this type of trigger will not be applied.
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Here you can choose how you will model the downtime task:
Delay (timeout/schedule) — you can set the task duration as a delay or use a schedule.
Delay (timeout/schedule) with resources — you can define the task duration as a delay or use a schedule and define the minimal logic for the resources that will execute this task.
If the resources you are using for the downtime task are also used elsewhere, the priority of the downtime task will be 0. If you need to define a more complex logic including the prioritizing of resources, you should define it in a separate flowchart and select Go to flowchart option in this parameter.
Delay until stopTask() is called — the task will continue running until its explicit termination by calling the stopTask() function. Go to flowchart — Alternative to modeling a task just with a delay, you can model it with a flowchart describing the process. The flowchart start should start with the ResourceTaskStart block specified in the Task start block field below.If the At downtime equipment property is set, the equipment starts the delay only after reaching the maintenance location.Value type: DowntimeDescriptor.TaskType
Valid values:
Downtime.TASK_DELAY — Delay (timeout/schedule)
Downtime.TASK_DELAY_WITH_RESOURCES — Delay (timeout/schedule) with resources
Downtime.TASK_WAIT_CALLBACK — Delay until stopTask() is called
Downtime.TASK_FLOWCHART — Go to flowchart -
[Visible if the Defined by parameter is set to Triggers and Task type is defined as Delay (timeout/schedule)]
The duration of the task.Value type: double
Default value: triangular(10, 20, 30) seconds
Local variable: T unit — the resource unit - Seize
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[Visible if Task type is defined as Delay (timeout/schedule) with resources]
Define the seize mode: (alternative) resource sets or units of the same pool.
For more details, see Resources.Syntax: boolean seizeFromOnePool
Default value: (alternative) resource sets — false -
[Visible if Seize is set to (alternative) resource sets]
Here you can define several alternative resource sets (add new list by clicking the Add list button). The resource set is chosen based on the availability of units.
For more details, see Resources.Local variable: agent — the agent -
[Visible if Seize is set to units of the same pool]
ResourcePool block from where the resources are requested.
For more details, see Resources.Local variable: agent — the agent -
[Visible if Seize is set to units of the same pool]
Expression evaluated to obtain the required number of resource units for the agent.Value type: int
Local variable: agent — the agent
Default value: 1 -
If selected (true), the seized resources will be sent to the specified location.
Value type: boolean
Default value: false
Local variables:
agent — the agent
T unit — the resource unit - Destination is
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[Visible if Send seized resources is selected]
Defines where the resources will be sent. The resources can be sent to:Agent — current agent location.
Network node — specified network node.
Attractor — specified attractor.Get value:Seize.DestinationType destinationType
Valid values:
Downtime.DEST_ENTITY — Agent
Downtime.DEST_NODE — Network node
Downtime.DEST_ATTRACTOR — Attractor -
[Visible if Destination is the Network node]
Network node where the seized resources will be sent. -
[Visible if Destination is: Attractor]
Attractor where the seized resources will be sent. -
[Visible if Send seized resources is selected]
Here you can select the behavior of the resources after they are released: they will either Return to home location or Stay where they are. -
[Visible if Task type is defined as Go to flowchart]
ResourceTaskStart block that starts the flowchart defining the task process.Local variable: T unit — the resource unit - At downtime equipment:
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[Compatible for Unit type: Jib Crane, Overhead Crane, moving resources defined by the ResourcePool or transporters defined by the TransporterFleet blocks.]
Here you choose where the equipment or its moving part (for the cranes) go at downtime. Has the following options:- stays where it is — equipment remains stationary during downtime.
- returns home — equipment relocates to its default location.
- goes to... — equipment moves to the specified location.
The maintenance location must be accessible for the equipment: either in the same network or inside the reach zone for the cranes.
Syntax: Downtime.MoveBeforeDowntime moveBeforeDowntime
Default value: self.MBD_STAY_WHERE_IT_IS
Valid values:
self.MBD_STAY_WHERE_IT_IS — stays where it is
self.MBD_RETURN_HOME — returns home
self.MBD_GO_TO — goes to the specified location - Maintenance location
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[Visible if At downtime equipment: goes to...]
Specifies the location to send the equipment during downtime. The equipment can relocate to:Node — specified network node.
Agent — current agent location.
Attractor — specified attractor.
x, y, z — specified coordinates.Syntax: Downtime.MoveTo.DestinationType downtimeDestinationType
Default value: self.MAINT_LOC_NODE
Valid values:
self.MAINT_LOC_NODE — Node
self.MAINT_LOC_AGENT — Agent
self.MAINT_LOC_ATTRACTOR — Attractor
self.MAINT_LOC_XYZ — Coordinates (x,y,z) -
[Visible if Maintenance location: Node]
Node where the equipment will be sent during downtime. -
[Visible if Maintenance location: Agent]
The agent to move to (it may be e.g. a particular resource unit of some other agent). -
[Visible if Maintenance location: Attractor]
Attractor where the equipment will be sent during downtime. -
[Visible if Maintenance location: (x, y, z)]
X,Y,Z coordinates of the point where equipment will be sent during downtime. Note that you define absolute coordinates, so you should make the point coordinates correspond to the node coordinates, otherwise equipment will move to the point residing outside the node. -
Here you choose whether you consider this task in the collected usage statistics as “busy” time, “idle” time, or not take it into account at all.
Default value: not collected
Get value:Seize.DestinationType destinationType
Valid values:
Downtime.USAGE_NOT_COUNTED — not collected
Downtime.USAGE_BUSY — counted as ‘busy’
Downtime.USAGE_IDLE — counted as ‘idle’
- Sets the priority of the task.
- Sets whether this task may preempt the task currently being executed, if any. In other words, true means that the unit will “drop its work” when this task is activated. If false, then the unit will finish all of its lower Priority tasks. Note that the true option has exceptions: the current task of the unit may have an “uninterruptible” option, No preemption.
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Specifies the policy for the task preemption:
No preemption — cannot be preempted (unit will be busy with this task until it is finished).
Terminate — may be preempted and will be terminated.
- On downtime triggered
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Here you can type the code that will be executed when this downtime task is triggered either by schedule, cycles, total or working time triggers, or manually.
Local variables:
unit — the resource unit - On start
- Here you can type the code that will be executed when the task starts. If at downtime the resource unit (transporter, crane, etc.) moves to the specified location, this code is executed only when it reaches the destination.
- On finish
- Here you can type the code that will be executed when the task finishes.
- On terminate
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[Visible if Preemption policy is defined as Terminate]
Here you can type the code that will be executed when the task has been terminated because of preemption.
| Function | Description |
|---|---|
| void restartTriggers(unit) |
Resets the countdowns of all triggers for the specified resource unit and starts waiting for the next triggering events. T unit — The unit which countdowns are to be reset. |
| void stopTask(unit) |
Stops the downtime task for the specified resource unit and restarts all triggers according to their settings. If the resource unit (transporter, crane, etc.) is currently moving to the specified maintenance location, the function call will be ignored. T unit — The unit which tasks are to be stopped. |
| boolean isActive(unit) |
Returns if the specified resource unit is currently executing the downtime task. T unit — The unit to check for downtime. |
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