What is a Shift?

Weekly shifts and breaks for activities and resources are defined using the Shift editor and may start and end at any minute of the day. Defining shifts for resources and activities in a model is only necessary when there are activities or resources with different work schedules. Otherwise the simulation can be run for a single block of time as though there was no off-shift time.

Shifts and breaks are defined by blocking out sections of time on a grid divided into days and hours. Once a weekly shift and break schedule has been defined, it may be saved in a shift file, which has an.SFT extension. This allows you to use the shift definition in models you create later.

Creating shifts in ProcessModel Shift Definition

This screen shot of the Shift Editor shows a shift defined to begin at 8 a.m. and end at 4:30 p.m. with two short breaks and a lunch break.

If the shift file opens blank but the model simulates correctly, make sure the file path is shorter than 255 characters.

 The shift file in a resource’s Shift tab can not be changed as conditions change in the simulation. Each resource can only have 1 shift for the entire simulation run. An attribute, variable, or scenario parameter can however be checked in the action logic. Then based on that parameter’s value, The appropriate resource with the desired shift can be selected.

How To – Open the Shift Editor

1. Open the Options dialog from the Simulation menu and click on the Files tab.


Click on the Shift tab of the properties dialog when a resource or activity is selected.

2. Click on the Create Shift File button.

Shift Editor

The Shift editor consists of a menu bar, Shift and Break mode buttons, time control buttons, and a grid representing one week of time. (All shown on the previous page.)

The remainder of this section describes the Shift Editor menus and the following procedures:

• Drawing a Block of Time for a Shift or Break
• Selecting a Block
• Resizing a Block
• Editing the Begin or End Time
• Deleting a Block
• Duplicating a Specific Day’s Shift
• Customizing Shift and Break Colors

Shift Editor Menus

The menus used in the Shift editor are accessible from the menu bar at the top of the editor and include the following:

File For opening shift files and saving open shift files.

Edit For deleting unwanted shift and break blocks. You may also duplicate a specific day of the shift. If you delete a shift, it deletes the shift as well as the breaks in the shift.

View For access to status and tool bars.

Options For customizing the colors which represent shifts and breaks.

Defining & Editing Shift & Break Blocks

You define a shift by selecting the Shift tool and drawing a shift block for each day that is to represent time on the shift. The break block tool can then be selected to draw break blocks over any portion of the defined shift. A break differs from off-shift time in that if a resource or activity is busy when a break time is scheduled to occur, the duration of the break time remains unchanged even if it could not immediately take effect. Off-shift time, in contrast, is reduced by any delay in going off shift, i.e., the activity comes back on shift at the scheduled time regardless of any delay in going off shift. This behavior typifies most real world situations.

When drawing a shift or break block, you must be sure to follow these rules:

• Shift blocks may not overlap with other shift blocks.
• Break blocks may only be drawn on top of shift blocks.
• Break blocks may not overlap or be adjacent to other break blocks.

How To – Draw a block

1. Click on the Shift or Break button to designate the type of block.

How to draw a shift block

2. Begin dragging the mouse on the grid at the day and time that the block should begin.

3. Release the mouse button at the time that the block should end. If you want to define a block more precisely than the grid allows, see Editing the Begin or End Time below.

  • If the block you draw is invalid, it is ignored and will not appear on the time grid.

How To – Select an existing block

• Click on the block. A border appears to show that the block has been selected.

Selecting an existing shift block

How To – Deselect a block

• Click on the selected block or click on the white area of the window.

How To – Resize a block

1. Select the block.

2. Click and drag the border of the block until the block is the desired size.

3. Release the mouse button.

How To – Edit a block’s begin or end time

1. Select the block.

2. Adjust the begin or end time accordingly using the buttons at the top of the screen. Click on the part of the time display you want to change (the hour, the minutes, or the AM/PM label). While that part of the display is highlighted, use the arrow buttons to increase or decrease the time, or to switch between AM and PM.

Editing a begin and end time of a shift block

How To – Delete a block

• Select a block and choose the Delete option from the Edit menu.


• Select a block and press the Delete key on the keyboard.

How To – Duplicate a shift block from one day to another day

1. Select any shift or break segment for the day you wish to duplicate.

2. Select Duplicate button from the toolbar. Duplicate toolbar button

3. In the shift schedule, click on the day to which you wish to copy the shift block.

  • To duplicate the same shift multiple times, hold the SHIFT key down while clicking were the shift is to be duplicated. Release the SHIFT key on the last duplication to exit the duplication mode.

How To – Change the color for shifts or breaks

1. From the Options menu, select Define Shift or Define Break.

2. Choose Colors under the Options menu. The colors dialog box appears.

Change the color for shifts or breaks

3. Click on the desired color.

More Information:

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