Chapter 3 – Model Elements
3.1 – Data Entry Rules for Names & Numbers
ProcessModel requires names and numbers to be entered following some simple rules. You should be familiar with these conventions to ensure that valid entries are made in your model.
Using descriptive, but short, names is recommended. The name you enter in the properties dialog for a resource, for instance, could be used in Action logic. If the name is too long and cumbersome, entering the logic statements could become tedious. If the name is too short or cryptic, you may not remember what it is later. However, you are free to adopt your own naming convention within the limits of the following rules:
• All letters are case insensitive (“A” is the same as “a”).
• Only the letters A through Z (upper or lower case), the digits (0-9) and the underscores “_” may be used. No other symbols or characters may be used in ProcessModel names.
• Names must begin with a letter of the alphabet or an underscore “_”. (e.g. Item5 or _Item5, but NOT 3_Item).
• Names must be single words (use underscores “_” for spaces).
• DO NOT use hyphens, e.g., High-Color would be invalid.
If no name is assigned to an object, a default name will be assigned. Some words are reserved, using one of these words will result in an underscore being appended to the name.
When entering numbers as a constant or within an expression, you should follow these rules:
• Do NOT use commas. The number 2,984.43 should be entered as 2984.43.
• Enter negative numbers using the dash (e.g.-345.23, not (345.23) or )
All values, such as quantity and time values, may be expressed as a number such as 23.5 or 9.25.
3.2 – Entities
Entities are the items or people being processed—e.g., products, documents, customers, etc. An entity is defined by selecting an entity shape from the shape palette, placing it on the layout, and entering any applicable information for that object in the properties dialog.
Entities are represented by graphics you choose from the palette. They will be shown as moving graphics during the process simulation. Using meaningful graphics in the model to represent entities in your real system will allow others to accurately visualize the flow through the process. They are processed at activities and are moved on routings from activity to activity. Entities can have an initial cost and collect additional costs from processing at activities, movement on routings and from the use of resources. There are hundreds of predefined entities in ProcessModel from all major industries.
Any ProcessModel graphic can be used as an entity (activity, resource, storage, link, label). To use a non entity graphic as an entity, double-click on the graphic and change the object type to Entity.
Each pre-defined entity graphic is assigned a number by ProcessModel. These numbers are used only for the NewGraphic statement (see NEWGRAPHIC).
ProcessModel contains several predefined entity shapes. Each predefined entity shape has the word ‘entity’ placed in parentheses in the shape name. However, you may also define custom entity shapes.
3.2.1 – General
Name The name of the entity (e.g. Customer, Product_A, etc.). The entity name is used primarily for decision making and reporting purposes. It is simply a descriptive attribute that may be changed during the simulation and tested for making process decisions. Entity statistics are reported based on the final name of the entity.
When you add an additional text label to an entity, place the label on the center of the entity. Otherwise, the entity will appear smaller during simulation.
Statistics: Yes / No This selection determines whether statistical information will be collected, displayed in the scoreboard, and reported in the Output Module for this entity.
The maximum number of entities that can be displayed in the simulation scoreboard is 12. That number cannot be modified.
Object Type Allows the type of object to be changed from Entity to something else.
3.2.2 – Cost
The identification of cost is optional and has no effect on the behavior of the model.
Initial cost The initial value assigned as the cost of each newly created entity (negative 1,000,000 to 1,000,000). Once assigned, the entity cost may be increased automatically during the simulation based on waiting time, activity time, and resource usage. This cost is added to the pre-defined Cost attribute of the entity.
Waiting cost The cost that is added to the entity per hour of waiting time. Cost may range from negative 1,000,000 to 1,000,000. This cost is added to the pre-defined Cost attribute of the entity.
To learn more about costs, see “ProcessModel and Activity-based Costing”.