Documentation

Counter Input

Read from one or multiple counter-input channels

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.

Ports

Output

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Data representing the state of a counter. The data type of the output values depends upon the capabilities of the board.

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

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

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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.

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.

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.

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.

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.

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.

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.

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]

Determines whether the software resets the counter to zero after reading its value. From the list, select 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.

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.

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.

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.

See Also

Introduced before R2006a

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