Analog Input

Read from one or multiple analog input channels

• Library:

• Simulink Desktop Real-Time

• 

Description

Connect to and read from specific analog input channels from your Simulink^® model. After you add an Analog Input block to your model, you can enter the parameters for its I/O driver.

Ports

Output

Analog Data — Analog-to-digital converter data read from input channels

vector

Result of A/D conversion of an analog signal. The data type and range of the output value depend on the capabilities of the board.

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

Missed Ticks — Missed tick count (optional)

double

In normal or accelerator modes, returns the number of timer ticks that your model lags behind the real-time kernel. When the model lags by more than Maximum missed ticks, the software reports an error and simulation stops.

Dependency

When you select Show “Missed Ticks” port, this port is visible.

Data Types: double

Parameters

Install new board — Register a board

< no board selected > (default)

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 >.

Dependency

When you select a board in the list of registered boards, the Delete current board and Board setup buttons are available.

Delete current board — Delete the current board

(button)

To delete the current board, click this button. The initial selection of the list of registered boards changes to < no board selected >.

Dependency

To activate this parameter, select a board in the list of registered boards.

When you delete the current board, the Delete current board and Board setup buttons are no longer available.

Board setup — Set up the board

(button)

To set up the board, click this button.

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

Dependency

To activate this parameter, select a board in the list of registered boards.

To deactivate this parameter, click Delete current board.

Sample time — Sample time of block

0.1 (default) | double

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

If you are using a fixed-step solver, enter the value that you entered as the Fixed step size configuration parameter or an integer multiple of that value.

Maximum missed ticks — Number of timer ticks by which your model can trail the kernel

10 (default) | integer

In normal or accelerator modes, enter the number of timer ticks that your model can lag behind the real-time kernel. When the model lags behind by this number or fewer timer ticks, the software assumes that the lag is temporary. It 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 — Send number of missed ticks to port Missed Ticks

'off' (default) | 'on'

In normal or accelerator modes, select this check box to send the number of missed ticks to output port Missed Ticks.

In external mode, the Missed Ticks port is zero.

Yield CPU when waiting — Yield CPU while kernel waits for hardware

'off' (default) | 'on'

In normal or accelerator modes, 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.

Input channels — Select analog input channels

1 (default) | vector

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

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

or

[1:8]

To select the first three analog input channels, enter:

[1,2,3]

Input range — Input range of analog inputs

board dependent

From the list, select the input range for the analog input channels that you entered for the Input channels parameter. For example, if the board has an input range of ±5 V, select -5 to 5 V.

If you want a different input range for different analog channels, add an I/O block for each different input range. The valid values depend upon the capabilities of the board.

Block output signal — Value type returned from block

Volts (default) | Normalized bipolar | Normalized unipolar | Raw

From the list, select from the following options:

• Volts — Returns a value equal to the analog voltage.

• Normalized bipolar — Returns a full range value of -1 to +1 regardless of the input voltage range.

• Normalized unipolar — Returns a full range value of 0 to +1 regardless of the input voltage range. For example, analog input ranges of 0 volts to +5 volts and of −5 volts to +5 volts are converted to 0 to +1.

• Raw — Returns a value from 0 through 2n -1. For example, a 12-bit A/D converter returns values from 0 through 212 -1 (0 to 4095). The advantage of this method is that the returned value is an integer with no round-off errors.

Output data type — Data type of block output

double (default) | single | int8 | uint8 | int16 | uint16 | int32 | uint32

From the list, select the type of data that the block outputs to the model. The valid values depend on the capabilities of the board.

Model Examples

Real-Time Controller

Build a simple closed-loop real-time controller by using Simulink Desktop Real-Time™. The output of the controlled plant is connected to the analog input of your data acquisition board. This signal is subtracted from the set point value generated by the signal generator and processed by a PID controller. The output of the controller drives the input of the plant by using the analog output of your data acquisition board.

Real-Time Filter

A real-time filter built using DSP System Toolbox™ and Simulink Desktop Real-Time™. The unfiltered signal is acquired by the analog input, passed through a filter designed by DSP System Toolbox and finally sent to analog output. Both the unfiltered and filtered signals are shown in real-time using the Scope block.