# Connectors

Purpose: As its name suggests, the job of the connector is to connect model elements. The software provides for two distinct types of connector: the action connector and the information connector. Action connectors are signified by a solid, directed wire. Information connectors are signified by a dashed wire. To select an info connector, click and hold the connector icon on the palette. Then select the info connector from the drop-down list that will appear.

Legal connector linkages are illustrated in Figure 4-24. As the diagram suggests, the software will not let you connect either an info or action connector directly into a stock. The only way to change the magnitude of a stock is through a flow.

Figure 4-24 Legal Connector Linkages

Selection and Placement:

- Select the connector icon by clicking once on the icon in the Building Block palette. To obtain the info connector, select the dashed arrow icon from the drop down list.

- Slide the cursor (the point of the arrow) to the place where the connector will start. This starting place must be within the boundary of a stock, flow regulator, converter, or decision process diamond on your screen.

- Click-and-hold. Drag the cursor to the target convertor, flow regulator, or decision process diamond. When you make contact, the target will turn gray. Release your click.

Note on Circular Connections: In drawing connector linkages, you may encounter an alert which tells you that circular connections are not allowed. Mechanically, this alert means that you have attempted to create a chain of converters and/or flows, such that one converter or flow ultimately depends upon itself. The software can not resolve the resultant simultaneous equations. To resolve the simultaneity, you must include a stock somewhere in the chain. The Introduction to Systems Thinking Guide provides a conceptual discussion of circular connections.

Surface Operations: Figure 4-25 details surface operations which may be performed on a connector.

Figure 4-25 Connector Surface Operations

Dialog Operations: Because the connector tool is used to indicate connections, it has no associated define dialog. The interrelationships between model variables are specified in the converter, flow, and stock building blocks.