Entity Output Switch

Output entities

• Library:

• SimEvents

• 

Description

The Entity Output Switch block allows you to select an output port for the departure of an entity among multiple entity output ports. The selected port can change during the simulation and you can choose the criterion for switching between output ports.

Here are some scenarios in which you might use an output switch:

• Entities advance to one of several queues based on efficiency or fairness concerns. For example, airplanes advance to one of several runways depending on queue length, or customers advance to the first available cashier out of several cashiers.

  Comparing different approaches to efficiency or fairness, by testing different rules to determine the selected output port of the output switch, might be part of your goal in simulating the system. For an example, see Route Vehicles Using an Entity Output Switch Block.

• Entities advance to a specific destination based on their characteristics. For example, parcels advance to one of several delivery vehicles based on the locations of the specified recipients.

• Entities use an alternate route in case the preferred route is blocked. For example, a communications network drops a packet if the route to the transmitter is blocked and the simulation gathers statistics about dropped packets.

Alternatively, you can use the Entity Gate block to control the flow of entities on a specific entity path. For more information, see Using Entity Priority to Sequence Departures.

Ports

Input

Port_1 — Input entity

scalar | vector | matrix

Input entity port for entities entering the block.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | enumerated | bus | fixed point

control — Incoming control entity

scalar

Input control port for the incoming control entity that determines the output port for the entities departing from the block.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | fixed point

Output

Port_1 — Output entity

scalar | vector | matrix

Output entity port for entities exiting the block.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | enumerated | bus | fixed point

Port_2 — Output entity

scalar | vector | matrix

Output entity port for entities exiting the block.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | enumerated | bus | fixed point

Parameters

Number of output ports — Specify the number of output ports

2 (default) | scalar

Number of output ports for entity departure.

Programmatic Use

Block Parameter: NumberOutputPorts

Type: character vector

Values: '2' | scalar

Default: '2'

Switching criterion — Choose the switching criterion

First port that is not blocked (default) | Round robin | From control port | From attribute | Equiprobable

Choose the criterion for switching between output ports.

• To output the entity to the first unblocked port, select First port that is not blocked.

  Assume an example where entities arriving at the Entity Output Switch block depart through the first entity output port that is not blocked, as long as at least one entity output port is not blocked. An everyday example of this approach is a single queue of people waiting for service by one of several bank tellers, cashiers, call center representatives, etc. Each person in the queue wants to advance as soon as possible to the first available service provider without preferring one over another.

• To output entities in a round robin fashion among the output ports, select Round robin.

• Select From control port to let the control port determine the selected port for entity departure. A control port will appear to input an anonymous entity carrying data with a value greater than 0 and smaller than or equal to the number of output ports to determine the active port.

• To specify an attribute that determines the output port, select From attribute. The attribute value is greater than 0 and smaller than or equal to the number of output ports to determine the active port.

  Consider the situation in which parcels are sorted among several delivery vehicles based on the locations of the specified recipients. If each parcel is an entity, then you can attach data to each entity to indicate the location of its recipient.

• To randomly select an output port for entity departure, select Equiprobable. Set the Seed to generate a random number and to determine the active output port.

Note

The block rounds a double precision value to the nearest integer less than or equal to its value as port selection. For instance, the value 0.3 is rounded of to 0 which is not a valid value for port selection.

Programmatic Use

Block Parameter: SwitchingCriterion

Type: character vector

Values: 'First port that is not blocked' | 'Round robin' | 'From control port' | 'From attribute' | 'Equiprobable'

Default: 'First port that is not blocked'

Initial port selection — Specify the output port at the start of the simulation

1 (default) | scalar

Select the initial port for the entity departure.

Dependencies

This parameter is visible when Switching criterion is set to Round robin or From control port.

Programmatic Use

Block Parameter: InitialPortSelection

Type: character vector

Values: '1' | scalar

Default: '1'

Switch Attribute name — Specify the attribute that determines the output port

Attribute1 (default) | character vector

Specify the attribute name used to switch the output port.

Dependencies

This parameter is visible when Switching criterion is set to From attribute.

Programmatic Use

Block Parameter: SwitchAttributeName

Type: character vector

Values: 'Attribute1' | character vector

Default: 'Attribute1'

Seed — Specify the seed

34567 (default) | scalar

Specify the seed for the random number generator to determine the output port.

Dependencies

This parameter is visible when Switching criterion is set to Equiprobable.

Programmatic Use

Block Parameter: Seed

Type: character vector

Values: '34567' | scalar

Default: '34567'

Model Examples

Route Vehicles Using an Entity Output Switch Block

Route vehicles to two different pumps in a gas station by controlling an Entity Output Switch block.

Resource Allocation from Multiple Pools

A technique for allocating resources from multiple resource pools. It shows how to choose a pool from which to draw a resource, based on given criteria.

Job Scheduling and Resource Estimation for a Manufacturing Plant

Model a manufacturing plant. The plant consists of an assembly line that processes jobs based on a pre-determined schedule. This example walks you through a workflow for:

Comparing Queuing Strategies

Have you ever been in a supermarket checkout and wondered why you are in the slowest line? This example shows how queuing systems can be modeled in SimEvents for this type of application. Two parallel versions of a simple model of a four register supermarket counter are presented - one that uses four separate queues and one with a single "serpentine" queue that feeds all registers.

Modeling a Kanban Production System

A production system that uses kanbans to manage production activities. Analysis of simulation results highlights problems in the system and suggests ways to improve its performance.

Effects of Communication Delays on an ABS Control System

How stochastic network traffic causes timing latency and uncertainty in an anti-lock braking system (ABS) that uses Control Area Network (CAN) communications. The model is representative of a real-world heavily-loaded network and also illustrates a domain-specific model of a distributed system. By including real-world timing effects in a model, you gain confidence about the behavior and robustness of your design before you test it in hardware.