Resource Downtime and Maintenance

A resource can go offline during a run in two different ways.

Random or scheduled downtime

The Availability tab makes a resource unavailable part of the time, either a random percentage or a regular interval (see Resource Availability). This downtime waits for the current entity to finish, so it never interrupts work in progress. Use it for breakdowns and unplanned stoppages.

Interrupting work

The shift Downtime Rule decides what happens to the entity a resource is working on when the resource goes offline:

• Finish Current Entity: finish the entity, then go offline (the default).
• Preempt and Wait: stop immediately; the entity waits for the same resource to return.
• Preempt and Pass: stop immediately; another available resource can pick up the work.
• Clear Queue First: finish the current entity and everything already queued, then go offline.

For scheduled maintenance, model the maintenance window as a shift (planned off-shift time) or as Time-mode availability. There is no separate maintenance object.

LegacyHow this worked in the previous version

Taking a resource off a task to perform another whether or not it has finished the original task. Then the resource returns to the interrupted task to finish it.

Suggested Technique

• Select the resource connection that is attached to the activity or routing that should always receive immediate attention.
• Check the Respond immediately box in the properties dialog of the resource connection.

Alternatively, you may use the GET or JOINTLYGET statements in the Action logic with a priority of 100 set off by a comma for the resource: GET Resource1, 100. (The 100 is an interruptive priority.) Connected resources will always be captured before resources specified in a GET statement. On the other hand, resource connections that free a resource occur after any Action logic for the activity.

Example: A receptionist must type up dictations and answer the phone. When the phone rings the receptionist must interrupt typing the current dictation and answer the phone.

TO DO: Make the connections and check the Respond immediately box as shown above.

Scheduled equipment maintenance

Scheduling equipment for regular maintenance so that it is unavailable for use during certain periods. (If maintenance is done during off hours, it can be safely ignored in the model.)

Suggested Technique

• Assign a shift to the resource to indicate scheduled downtime (for maintenance or other purposes). For information on creating and assigning shifts, see Defining & Editing Shift & Break Blocks.

Whenever possible, use the shift schedule for scheduled interruptions.