Digital Output

Select and connect digital output lines or channels

Library

Real-Time Windows Target™

Description

The Digital Output block allows you to select and connect specific digital lines or channels to your Simulink® model. After you have added a Digital Output block to your model, you can enter the parameters for its I/O driver. The following procedure uses the HUMUSOFT® AD512 I/O board as an example.

Parameters

Sample time

Enter a value representing how frequently you want the block to execute and interact with the I/O hardware. The block will also synchronize 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 you entered in the Fixed step size box from the Configuration Parameters dialog box, or an integer multiple of that value.

Maximum missed ticks

Enter the number of timer ticks that your model can lag behind the real-time kernel. When the model lags by more than this number, the block reports an error and simulation stops. Otherwise, simulation continues even if some ticks are missed.

Show "Missed Ticks" port

Select this check box to display the current number of missed ticks as a block output.

Yield CPU when waiting

Select this check box to grant other programs more CPU time while the kernel waits for a response from the hardware.

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 eight digital output channels on the AD512 board, 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 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 (8 digital lines) with an initial value of 25, enter [25]. For two bytes (16 digital lines) with initial values of 25 and 50, enter [25 50].

First value

Enter a final value for each digital output channel 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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