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Count Up Down Function Block

LabVIEW 2009 Real-Time Module Help

Edition Date: June 2009

Part Number: 370622G-01

»View Product Info

Owning Palette: Timer Function Blocks

Requires: RT Module

Counts up to or down from a number you specify using the preset value input.

Details  

Dialog Box Options
Block Diagram Inputs
Block Diagram Outputs

Dialog Box Options

ParameterDescription
InputsContains the following configuration options:
  • Terminal name—Contains the name of the block diagram terminal to configure.
  • Visible?—Specifies whether to display the terminal on the block diagram.
  • Variable scope—Specifies the availability and scope of the variable associated with the terminal. Select Single-process to use a single-process shared variable. Select Network-published to use a network-published shared variable. Select No Variable if you do not want to use a terminal variable. To minimize overhead, include function block terminal variables only when necessary. If you change the Variable scope to No Variable after creating the function block instance, LabVIEW deletes the terminal variable.
  • Data source—Specifies the data source of the input. Select Terminal to wire the input value to the terminal on the block diagram. Select Variable to supply the input value to the function block through the associated terminal variable, if available. Select Default value to use the Default value. The Variable data source option is not available if you select No Variable under Variable Scope. If you select Terminal as the data source and leave the block diagram terminal unwired, LabVIEW uses the Default value.
  • Default value—Specifies the default value of the input. If you select Variable as the data source, LabVIEW uses this value as the initial value of the variable. If you select Default value as the data source, LabVIEW uses this value for every iteration of the function block.
OutputsContains the following configuration options:
  • Terminal name—Contains the name of the block diagram terminal to configure.
  • Visible?—Specifies whether to display the terminal on the block diagram.
  • Variable scope—Specifies the availability and scope of the variable associated with the terminal. Select Single-process to use a single-process shared variable. Select Network-published to use a network-published shared variable. Select No Variable if you do not want to use a terminal variable. To minimize overhead, include function block terminal variables only when necessary. If you change the Variable scope to No Variable after creating the function block instance, LabVIEW deletes the terminal variable.

Block Diagram Inputs

ParameterDescription
error in (no error)Describes error conditions that occur before this node runs.
loadSets counter value to preset value.
resetSets counter value to zero.
preset valueSpecifies the number to count up to or down from.
count downSpecifies whether to decrement counter value. Each rising edge of this input triggers counter value to decrease by one.
count upSpecifies whether to increment counter value. Each rising edge of this input triggers counter value to increase by one.

Block Diagram Outputs

ParameterDescription
error outContains error information. This output provides standard error out functionality.
counter valueReturns the current value of the counter.
doneIndicates when the function block finishes counting down.

Count Up Down Details

The timing of this function block depends on the rate of the Timed Loop or While Loop in which you place the function block. For example, if you need the function block to update with millisecond resolution, you can place the function block in a Timed Loop configured to execute every millisecond.

The following timing diagram illustrates the behavior of this function block.


 

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