Discrete First-Order Hold Function

Simulation VI and Function

Discrete First-Order Hold Function

Owning Palette: Discrete Linear Systems Functions

Installed With: Control Design and Simulation Module

Extrapolates the value of the output signal based on the first derivative of the input signal.

Details  Example

Dialog Box Options
Block Diagram Inputs
Block Diagram Outputs
 Place on the block diagram  Find on the Functions palette

Dialog Box Options

ParameterDescription
Polymorphic instanceSpecifies whether this function is Scalar or Vector. The default value is Scalar.
ParametersLists all the parameters associated with this function. Select a parameter from this list to configure the parameter. When you select a parameter, the parameter and its associated Parameter source control appear in the Parameter Information section of the configuration dialog box.
PreviewDisplays a graphical preview, if available, of the function output or configuration.
Parameter InformationContains the parameters you can configure for this function. You must select a parameter from the Parameters list to make that parameter and its associated Parameter source control visible in the Parameter Information section of the configuration dialog box.
Parameter sourceSpecifies whether you configure this parameter using the Configuration Dialog Box or a Terminal on the simulation diagram. The default value is Configuration Dialog Box. If you select Terminal, LabVIEW displays an input for that parameter on the simulation diagram, and you can wire values to that input to configure this function programmatically. If you select Configuration Dialog Box, LabVIEW removes that input from the simulation diagram. You then must set the value for this parameter inside the configuration dialog box.
sample period (s)Specifies the length of the discrete time step, in seconds, of this function. If you enter a value of –1, this function inherits the discrete time step you specify for the simulation diagram. Otherwise, the value of sample period (s) must be a multiple of the discrete time step you specify for the simulation diagram. The default value of sample period (s) is 1.
sample skew (s)Specifies the length of time by which you want to delay the execution of this function. The default value is 0. The value of this parameter must satisfy the following relationship:

0 ≤ sample skew (s)sample period (s)

Block Diagram Inputs

ParameterDescription
sample period (s)Specifies the length of the discrete time step, in seconds, of this function. If you enter a value of –1, this function inherits the discrete time step you specify for the simulation diagram. Otherwise, the value of sample period (s) must be a multiple of the discrete time step you specify for the simulation diagram. The default value of sample period (s) is 1.
sample skew (s)Specifies the length of time by which you want to delay the execution of this function. The default value is 0. The value of this parameter must satisfy the following relationship:

0 ≤ sample skew (s)sample period (s)
inputSpecifies the input to this function.

Block Diagram Outputs

ParameterDescription
outputSpecifies the output of the system.

Discrete First-Order Hold Details

The following equation defines the output of this function.

wherey is the output
u is the input
t is the current simulation time
ti is the initial simulation time
tk = ti + sample skew (s) + k * sample period (s), for k = 1, 2, 3, …

Feedthrough Behavior

All input/output pairs of this function have direct feedthrough behavior.

Example

Refer to the SimEx first-order-hold VI in the labview\examples\Control and Simulation\Simulation\Discrete Linear directory for an example of using the Discrete First-Order Hold VI.

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