Documentation

Digital Output

Connect to and write to digital output lines or channels

Library

Simulink® Desktop Real-Time™

Description

Connect to and write to specific digital lines or channels from your Simulink model. After you have added a Digital Output block to your model, you can enter the parameters for its I/O driver.

Parameters

Install new board

Click this button to register a board with Simulink Desktop Real-Time.

When you click Install new board, the software displays a list of manufacturers of supported boards. When you select a manufacturer, the software displays a list of boards available from that manufacturer. When you select a board, the software adds the board to the list of registered boards and makes that board the current board.

By default, the initial selection in the list of registered boards is < no board selected >. When you select a board in the list, the Delete current board and Board setup buttons become active.

Delete current board

Click this button to delete the current board. The initial selection of the list of registered boards changes to < no board selected >, and the Delete current board and Board setup buttons become inactive.

Board setup

Click this button to set up the board.

A board-specific dialog box opens for you to use to set up the board. For more information to set up the board, see the board manufacturer documentation.

Sample time

Enter a value representing how frequently you want the block to execute and interact with the I/O hardware. The block also synchronizes your model with the real-time clock at this sample rate.

    Tip   If you are using a fixed-step solver, you must enter the value that you entered in the Fixed step size box in the Configuration Parameters dialog box, or an integer multiple of that value.

Maximum missed ticks

In Normal Mode, enter the number of timer ticks that your model can lag behind the real-time kernel. When the model lags by this number or less, the software assumes that the lag is temporary and allows the model to catch up, even if the model misses some ticks. When the model lags by more than this number, the software reports an error and simulation stops.

In External Mode, the software ignores this value.

Show "Missed Ticks" port

In Normal Mode, select this check box to display the number of missed ticks as a block output.

In External Mode, The "Missed Ticks" port displays zero.

Yield CPU when waiting

In Normal Mode, select this check box to grant other programs more CPU time while the kernel waits for a response from the hardware.

In External Mode, the software ignores this value.

Output channels

Enter a channel vector that selects the digital output channels you are using on this board. The vector can be any valid MATLAB® vector form. For example, to select the first eight digital output channels, enter:

[1,2,3,4,5,6,7,8] or [1:8]

If you want to use the first four digital output lines, enter:

[1,2,3,4]

If you have one 8-bit digital channel, enter [1]. If you have two 8-bit digital channels, enter [1 9], and from the Channel mode list, choose Byte.

Channel mode

From the list, choose from one of the following:

  • Bit — Expects a value of 0 or 1.

  • Byte — Expects a value of 0 to 255 that is converted to one digital channel of eight digital lines.

Initial value

Enter the initial values for each digital output line or channel that you entered in the Output channels box. For example, if you entered [1,2,3,4] in the Output channels box, and you want initial values of 0 and 1, enter:

[0,0,1,1]

If you choose Byte from the Channel mode list, enter a value between 0 and 255 for each digital output channel. For example, for one byte (eight digital lines) with an initial value of 25, enter [25]. For two bytes (sixteen digital lines) with initial values of 25 and 50, enter [25 50].

First value

Enter a final value for each digital output channel that you entered in the Output channels box. For example, if you entered [1,2,3,4] in the Output channels box, and you want final values of 0, enter:

[0,0,0,0]

If you choose Byte from the Channel mode list, enter a value between 0 and 255 for each digital output channel.

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