Documentation

Counter Input

Connect to and read from counter input channels

Library

Simulink® Desktop Real-Time™

Description

Connect to and read from specific counter input channels into your Simulink model. After you have added a Counter Input 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.

Input channels

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

[1,2,3,4] or [1:4]
Reset after read

Determines if the software should reset the counter to zero after reading its value. From the list, choose one of the following options:

  • never — Do not reset after reading.

  • always — Always reset after reading.

  • level — Reset after reading if the block input is nonzero. Adds an input to the Counter Input block.

  • rising edge — Reset after reading if the block input changes from zero to nonzero between the last two successive readings. Adds an input to the Counter Input block.

  • falling edge — Reset after reading if the block input changes from nonzero to zero between last two successive readings. Adds an input to the Counter Input block.

  • either edge — Reset after reading if the block input changes either from zero to nonzero or from nonzero to zero between the last two successive readings. Adds an input to the Counter Input block.

Clock input source

Determines the clock input source to increment the counter. From the list, select:

  • input pin rising edge — Clock edge low-to-high transitions

  • input pin falling edge — Clock edge high-to-low transitions

  • internal clock — Internal time base

    If you set the Gate input functionality parameter to enable when high, latch & reset on edge, or enable when low, latch & reset on edge, you can measure positive or negative pulse lengths in units of the internal time base. You can use this combination with National Instruments® drivers for pulse width measurement.

Not all counter chips support selecting the input edge. In this case, only supported options appear in the list..

Gate input functionality

Defines the action of the counter gate input pin. From the list, select:

  • none — Enable counting unconditionally, ignoring gate input.

  • enable when high — Disable counting when gate input is low and enable counting when gate input is high.

  • enable when low — Disable counting when gate input is high and enable counting when gate input is low.

  • start on rising edge — Disable counting until low-to-high gate transition occurs.

  • start on falling edge — Disable counting until high-to-low gate transition occurs.

  • reset on rising edge — Reset counter to zero when low-to-high gate transition occurs.

  • reset on falling edge — Reset counter to zero when high-to-low gate transition occurs.

  • latch on rising edge — Store count in register when low-to-high gate transition occurs. Return contents of register.

  • latch on falling edge — Store count in register when high-to-low gate transition occurs. Return contents of register.

  • latch & reset on rising edge — Store count in register and then reset counter to zero when low-to-high gate transition occurs. Return contents of register.

  • latch & reset on falling edge — Store count in register and then reset counter to zero when high-to-low gate transition occurs. Return contents of register.

  • enable when high, latch & reset on edge — Disable counting while gate input is low. Start counting when low-to-high gate transition occurs. Count while gate input is high. Store count in register and then reset counter to zero when high-to-low gate transition occurs. Return contents of register.

    If you set the Clock input source parameter to internal clock, you can measure positive pulse lengths in units of the internal time base. You can use this combination with most National Instruments drivers for pulse width measurement.

  • enable when low, latch & reset on edge — Disable counting while gate input is high. Start counting when high-to-low gate transition occurs. Count while gate input is low. Store count in register and then reset counter to zero when low-to-high gate transition occurs. Return contents of register.

    If you set the Clock input source parameter to internal clock, you can measure negative pulse lengths in units of the internal time base. You can use this combination with National Instruments drivers for pulse width measurement.

Not all counter chips support all gate input modes. Only supported modes appear in the list.

Output data type

From the list, select the type of data that the block outputs to the model.

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