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Conveyor System

Transport entities

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  • Conveyor System block

Libraries:
SimEvents

Description

The Conveyor System block transports entities across the surface of a conveyor. Entities enter the block by sliding onto the conveyor surface and they depart the block by sliding off. You can specify the speed of the conveyor. If the conveyor speed is variable, a second input port appears on the block to accept anonymous entities that carry data for specifying the new conveyor speed. Use this block to model transportation applications involving production systems, or logistical systems.

In the Conveyor System block:

  • You can specify the speed and the surface length of the conveyor. You can specify the length and the minimum distance between the transported entities.

    Simple stick diagram showing conveyor length, entity length, minimum distance between entities and conveyor speed.

  • Entities slide into the conveyor surface and an entity is considered as inside the conveyor surface when its front side coincides with the surface entry.

    Simple stick diagram showing the front end of an entity lined up with the surface entry of a conveyor.

  • Entities slide out of the conveyor surface and an entity is considered as outside the conveyor surface when its back side coincides with the surface entry.

    Simple stick diagram showing the back end of an entity lined up with the surface entry.

  • Conveyor speed determines the total time between an entity entry to the surface and its exit from the surface.

    Entity can enter and exit the conveyor surface provided that:

    • There are no other entities blocking the entity when the Blocked output behavior is set to Accumulate.

    • The conveyor surface is not paused when the Blocked output behavior is set to Pause. For more information, see Blocked output behavior.

    Simple stick diagram showing an entity entering, moving over and exiting a conveyor.

    For instance, suppose that the conveyor length is 10, entity length is 1, and conveyor speed is 5. Then, it takes 2.2 simulation time for the entity to depart the surface. 10/5 = 2 to travel through the surface and 1/5 = 0.2 to depart from the surface because its length is 1.

  • After an entity enters the conveyor surface, the next entity enters after the first one travels to the specified minimum distance between entities.

    Simple stick diagram showing an entity entering the conveyor only after the entity in front has reached the specified minimum distance between entities.

  • The capacity of the conveyor system is the maximum number of entities allowed on the surface. The capacity is determined by the total surface length, entity length, and the minimum distance between entities.

    For example, suppose that the entity length is 1 meter, conveyor system surface length is 100 meters, and the distance between entities is 15 meters. The capacity of the conveyor system becomes 6 entities.

    Simple stick diagram illustrating how six entites of length 1 meter can fit onto a conveyor system of surface length 100 meters with distance between entities as 15 meters.

  • When using the Conveyor length, Conveyor speed, Minimum distance between entities, and Entity length value parameters ensure that the values are consistent with each other.

    For example, specify the entity length of 10 cm and a conveyor system of length 100 m to achieve consistency:

    • Set the Conveyor length parameter to 100.

    • Set the Entity length parameter to 0.1.

Examples

Job Scheduling and Resource Estimation for a Manufacturing Plant

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:

Ports

Input

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Input entity port for entities entering the queue. Entities are not accepted by the block when the speed of the conveyor is 0.

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

Input port for anonymous entities entering the block. The entity carries data that specifies the new conveyor speed upon its arrival. The entity data must be a non-negative value between 0 and Inf. The new speed applies to all entities in the block including the incoming and existing ones.

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

Output

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Output entity port for entities leaving the queue

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

Selecting this check box outputs the number of entities that have exited the block.

Dependencies

To enable this port, select the Statistics > Number of entities departed, d check box.

Data Types: double

Selecting this check box outputs the number of entities in the block.

Dependencies

To enable this block, select the Statistics > Number of entities in block, n check box.

Data Types: double

Selecting this check box outputs the value 1 for a pending entity in the block, and 0 otherwise.

Dependencies

To enable this port, select the Statistics > Pending entity in block, pe.

Data Types: double

Selecting this check box outputs the conveyor speed.

Dependencies

To enable this port, select the Statistics > Conveyor speed, s.

Data Types: double

Parameters

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Length of surface that entities travel on. For more information, see Description.

Programmatic Use

Block Parameter: mConveyorLength
Type: character vector
Values: '100' | scalar
Default: '100'

Speed of surface that entities travel on. The speed can take values greater than 0 and its value can be zero only when the Variable conveyor speed check box is selected. For more information, see Description.

Programmatic Use

Block Parameter: mConveyorSpeed
Type: character vector
Values: '1000' | scalar
Default: '1000'

Minimum physical separation entities maintain while moving across the conveyor system. For more information, see Description.

Programmatic Use

Block Parameter: mMinDisBetEntity
Type: character vector
Values: '0' | scalar
Default: '0'

Provide entity length, selected from the drop-down list.

Dependencies

  • Dialog — Selecting this option enables the Entity length value parameter.

  • Attribute — Selecting this option enables the Entity length attribute name parameter.

Programmatic Use

Block Parameter: mEntityLengthSource
Type: character vector
Values: 'Dialog' | 'Attribute'
Default: 'Dialog'

Length of entities, specified as a numeric value. For more information, see Description.

Dependencies

To enable this parameter, select Dialog for Entity length source.

Programmatic Use

Block Parameter: mEntityLength
Type: character vector
Values: '1' | scalar
Default: '1'

Name of entity length attribute, specified as a character vector.

Dependencies

To enable this parameter, select Attribute for Entity length source.

Programmatic Use

Block Parameter: mEntityLengthAttrName
Type: character vector
Values: 'Length' | character vector
Default: 'Length'

Behavior when output is blocked, selected from drop-down list:

  • Accumulate — Accumulate entities. In Accumulate mode, an entity continues to move on the conveyor surface until its movement is blocked by another entity ahead.

    For example, if one or more entities are extracted out of the conveyor surface by the Entity Find block, entities that are behind the extracted entity continue to move forward until they occupy the empty space due to the extraction.

  • Pause — Pause conveyor system. In Pause mode, all entities on the conveyor surface stop and move together. The conveyor surface stops moving when an entity at the exit is unable to depart. During the pause, the conveyor system does not accept new entities.

  • Error — Return an error. In Error mode, when an entity is blocked from entering the conveyor surface the error is displayed.

Programmatic Use

Block Parameter: mOutputBlockedOpt
Type: character vector
Values: 'Accumulate' | 'Pause' | 'Error'
Default: 'Accumulate'

Conveyor behavior when the conveyor surface is full.

Selected check boxon

Return an error if the conveyor system is full.

Unselected check boxoff

Do not return an error if the conveyor system is full.

Programmatic Use

Block Parameter: mErrorUponFullOpt
Type: character vector
Values: 'on' | 'off'
Default: 'on'

Specify if the conveyor system has constant or variable speed.

Unselected check boxoff

Constant speed conveyor system. You can specify the speed using the Conveyor speed parameter.

Selected check boxon

Variable speed conveyor system. An input port appears to accept anonymous entities which carry data to specify the new conveyor speed.

Programmatic Use

Block Parameter: mIsVariableSpeed
Type: character vector
Values: 'on' | 'off'
Default: 'on'

Number of entities that have departed the block.

Programmatic Use

Block Parameter: mNumEntitiesDepOpt
Type: character vector
Values: 'on' | 'off'
Default: 'off'

Outputs the number of entities present in the block.

Programmatic Use

Block Parameter: mNumEntitiesInBlockOpt
Type: character vector
Values: 'on' | 'off'
Default: 'off'

Indicates whether an entity that is yet to depart is present in the block. The value is 1 for a pending entity, and 0 otherwise.

Programmatic Use

Block Parameter: mEntityPendingOpt
Type: character vector
Values: 'on' | 'off'
Default: 'off'

Outputs the number of extracted entities which are pulled out from this block by the Entity Find block. When an entity is extracted, Number of entities departed, d,and Number of entities in block, n statistics are updated accordingly. For more information about finding and extracting entities, see Find and Extract Entities in SimEvents Models.

Programmatic Use

Block Parameter: mNumExtractedFromBlockOpt
Type: character vector
Values: 'on' | 'off'
Default: 'off'

Outputs the speed of the conveyor during the course of the simulation.

Programmatic Use

Block Parameter: mConveyorSpeedOpt
Type: character vector
Values: 'on' | 'off'
Default: 'off'

Version History

Introduced in R2017b

See Also

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