Using Simulink

Outport

Create an output port for a subsystem or an external output.

Library

Signals & Systems

Description

Outports are the links from a system to a destination outside the system.

Simulink assigns Outport block port numbers according to these rules:

• It automatically numbers the Outport blocks within a top-level system or subsystem sequentially, starting with 1.
• If you add an Outport block, it is assigned the next available number.
• If you delete an Outport block, other port numbers are automatically renumbered to ensure that the Outport blocks are in sequence and that no numbers are omitted.
• If you copy an Outport block into a system, its port number is not renumbered unless its current number conflicts with an Outport block already in the system. If the copied Outport block port number is not in sequence, you must renumber the block or you will get an error message when you run the simulation or update the block diagram.

Outport Blocks in a Subsystem

Outport blocks in a subsystem represent outputs from the subsystem. A signal arriving at an Outport block in a subsystem flows out of the associated output port on that Subsystem block. The Outport block associated with an output port on a Subsystem block is the block whose Port number parameter matches the relative position of the output port on the Subsystem block. For example, the Outport block whose Port number parameter is 1 sends its signal to the block connected to the top-most output port on the Subsystem block.

If you renumber the Port number of an Outport block, the block becomes connected to a different output port, although the block continues to send the signal to the same block outside the subsystem.

When you create a subsystem by selecting existing blocks, if more than one Outport block is included in the grouped blocks, Simulink automatically renumbers the ports on the blocks.

The Outport block name appears in the Subsystem block icon as a port label. To suppress display of the label, select the Outport block and choose Hide Name from the Format menu.

Outport Blocks in a Conditionally Executed Subsystem

When an Outport block is in an enabled subsystem, you can specify what happens to its output when the subsystem is disabled: it can be reset to an initial value or held at its most recent value. The Output when disabled pop-up menu provides these options. The Initial output parameter is the value of the output before the subsystem executes and, if the reset option is chosen, while the subsystem is disabled.

Outport Blocks in a Top-Level System

Outport blocks in a top-level system have two uses: to supply external outputs to the workspace, which you can do by using either the Simulation Parameters dialog box or the sim command, and to provide a means for analysis functions to obtain output from the system.

• To supply external outputs to the workspace, using the Simulation Parameters dialog box (see Saving Output to the Workspace) or the sim command (see sim). For example, if a system has more than one Outport block and the save format is array, the following command

[t,x,y] = sim(...);

writes y as a matrix, with each column containing data for a different Outport block. The column order matches the order of the port numbers for the Outport blocks.

If you specify more than one variable name after the second (state) argument, data from each Outport block is written to a different variable. For example, if the system has two Outport blocks, to save data from Outport block 1 to speed and the data from Outport block 2 to dist, you could specify this command:

[t,x,speed,dist] = sim(...);

• To provide a means for the linmod and trim analysis functions to obtain output from the system. For more information about using Outport blocks with analysis commands, see Chapter 5.

Numeric and Data Type Support

An Outport block accepts complex or real signals of any MATLAB data type as input. The numeric and data type of the block's output is the same as that of its input. The elements of a signal array connected to an Outport block can be of differing numeric and data types except in the following circumstance. If the outport is in a conditionally executed subsystem and the initial output is specified, all elements of an input array must be of the same numeric and data type.

Simulink's data type conversion rules apply to an outport's Initial output parameter. If the initial value is in the range of the block's output data type, Simulink converts the initial value to the output data type. If the specified initial output is out of range of the output data type, Simulink halts the simulation and signals an error. Note that the block's output data type is the data type of the signal connected to its input.

Parameters and Dialog Box

Port number

The port number of the Outport block.

Output when disabled

For conditionally executed subsystems, what happens to the block output when the system is disabled.

Initial output

For conditionally executed subsystems, the block output before the subsystem executes and while it is disabled.

Characteristics

Sample Time	Inherited from driving block
Dimensionalized	Yes

Mux

Polynomial