Switch

Switch: Enabling an item to choose alternate paths

Switches enable items to dynamically select from a number of possible paths. They are classified as “Logical Only” and cannot hold items.

They are typically used in situations where items select shortest queues (ie. people queuing for ATM machines) or where an item can be processed by a number of servers.

The switch will choose from any paths along which the item can proceed (ie. flows which are not blocked). If none are available, the item will become blocked until one becomes available.

Different path selection rules are available through various switch 'Modes'.

Path selection can also be made according to attributes. This enables a switch to direct an item according to a characteristic the item carries, or according to an attribute of the model, either of which may be changed during the course of a model run.

Switches can also act like a gate, blocking the progress of items.

Due to the way Planimate® manages the progress of items, gating is a setting that is turned off or on.

Switch States

Switches are always idle.

They do not interact directly with items in the run of a model but rather influence the path that items going through the switch take.

Switch Modes

Some Switch modes provide a convenient means of rule-setting that require a single setting, which Planimate® manages for you during the run.

Random Choice from Available Path

Each available path has an equal chance of being selected. For more details see Random Choice from Available Path.

First Available Path

The switch selects the path with the lowest path number that is available. For more details see First Available Path.

Shortest Queue

The switch then selects the path that links to the queue or objects with the shortest length, i.e. the least number of items held by it. For more details see Shortest Queue.

Sequential

The switch will cycle between the available paths beginning with the lowest path number. For more details see Sequential.

Other switch modes enable you to construct sophisticated rule sets, which can determine the path for an item based on conditions within the model, or the item’s own attributes.

Attribute

The switch uses the value of an Attribute to assign a path for the item. For more details see Attribute Based Branching.

Condition

This mode enables you to specify a test for the Switch to perform when an item looks through it. For more details see Single Condition Based Branching.

Multiple Conditions

This mode enables you to construct a sequence of tests for the Switch to perform when an item looks through it. For more details see Multiple Condition Based Branching.

Gating

This option sets whether the switch can block items or not. Different icon colours indicate what Gating has been set.

Icon

Gating Options and When to Use them

• Switch Cannot Block Items

You can safely assume, or it is your design intent, that items will never be blocked from passing through this switch during a model run.

• Switch Can Block Items

You want or believe that items attempting to pass through the switch may become blocked, and forced to wait before moving on.

About Selecting a Gating Option

Switches do not have any capacity, so an item cannot become blocked at a switch, rather it will become blocked at the object upstream that is feeding the switch.

Refer to Switch Options for more details.

Refer to Editing Object Properties for information about editing properties common to all objects.