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Resources and Shifts
The Shift block
☞ If a Shift block is used in a model, statistics in the Queue blocks will probably not accurately reflect utilization, etc.
Status connectors
The Shift block’s value input connector (StatusIn) can be used to override the shift schedule. If the input connector is less than 0.5, the Shift is considered off shift; this will override any value found in the Shift block’s dialog table. If the input connector is greater than 0.5, the shift schedule from the dialog table is used.
The Shift’s value output connector (StatusOut) reports the current shift status (ON = 1 or OFF = 0 for On/Off type Shifts, or the number for Number type Shifts).
Shift models
The following models show how to use the Shift block in typical modeling situations. They also illustrate how the two types of Shift, On/Off and Number, are used in simulations.
☞ The models are located in the \Examples\Discrete Event\Resources and Shifts folder.
On/Off type example
In the “Shift On and Off” model at right, an On/Off type of shift turns the Activity block on for 4 hours in the morning, off for 1 hour at lunch, back on for 4 hours in the afternoon, and off again in the eve- ning until the next morning. The schedule, named “Day Shift”, is set in the Shift block; the dialog of the Activity block is set to Use Shift: Day Shift, which causes the Activity to go on or off according to that schedule.
The model contains a cloned graph
from the plotter. On the graph the
upper (blue) line reflects this 24-
hour shift cycle for seven days, a
total of 168 hours. Observe how
the lower (red) line, which is plotted against the Y2 axis, reflects the queue length’s dynamics during the various on and off shift periods.
Shift On and Off model
Discrete Event

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