SR Bistable Function Block

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LabVIEW 2009 Real-Time Module Help

Edition Date: June 2009

Part Number: 370622G-01

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Owning Palette: Bistable/Flip-Flop Function Blocks

Requires: RT Module

Creates a set-dominant latch, also known as a flip-flop.

If output is TRUE, output remains TRUE until the function block receives a reset pulse. If output is FALSE, output remains FALSE until the function block receives a set pulse. If set and reset are both TRUE, output is TRUE.

Example

Dialog Box Options

Block Diagram Inputs

Block Diagram Outputs

Dialog Box Options

Parameter	Description
Inputs	Contains 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.
Outputs	Contains 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.

Parameter

Description

Inputs

Contains 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.

Outputs

Contains 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

Parameter	Description
error in (no error)	Describes error conditions that occur before this node runs.
reset	Asserts the reset signal.
set	Asserts the set signal.

Block Diagram Outputs

Parameter	Description
error out	Contains error information. This output provides standard error out functionality.
output	Returns the Boolean value stored in the bistable function block.

Example

Refer to the Function Blocks.lvproj in the labview\examples\functionblocks directory for an example of using the SR Bistable VI.