Table Of Contents

Watchdog Timer Configure (G Dataflow)

Last Modified: January 12, 2018

Configures a new watchdog timer object to control a watchdog timer.

Configuring a watchdog timer object does not start the watchdog timer. Use the Watchdog Timer Restart node to start the watchdog timer.

Programming Patterns
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desired timeout

Time in seconds that you want the watchdog timer to wait before it expires.

Setting an Appropriate Timeout

The appropriate range of timeout values depends on the specific performance characteristics and up-time requirements of the embedded application. You must set the timeout long enough so that the watchdog timer does not expire due to acceptable levels of system jitter. However, you must set the timeout short enough so that the system can recover from failure quickly and meet system up-time requirements.

Default: 1 s

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expiration actions

Actions that the node takes when the watchdog timer expires.

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Note  

Not all targets support all actions. Refer to your real-time target hardware documentation for information about supported actions.

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restart system

Boolean value that specifies whether to restart the real-time controller when the watchdog timer expires.

True Restarts the real-time controller and ignores restart LabVIEW Runtime and trigger occurrence.
False Does not restart the real-time controller.

Default: False

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restart LabVIEW Runtime

Boolean value that specifies whether to restart the current application on the controller when the watchdog timer expires.

True

Restarts the current application on the controller and ignores trigger occurrence.

False

Does not restart the current application on the controller.

Default: False

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trigger occurrence

Boolean value that specifies whether to trigger the occurrence without restarting the real-time controller or the current application on the controller when the watchdog timer expires.

True Triggers the occurrence without restarting the real-time controller or the current application on the controller.
False Does not trigger the occurrence.

Default: False

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trigger protocol

Protocol used for trigger action on the PXI bus when the watchdog timer expires.

Name Description
active high Sets the trigger action to be active when the line is high.
active low Sets the trigger action to be active when the line is low.
open collector Sets the trigger action to operate as an open collector output.

Default: active high

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trigger line

Trigger line on the PXI bus to be asserted when the watchdog timer expires.

If you specify a trigger line that has been reserved elsewhere, the watchdog timer object overwrites the existing value on the trigger line when the watchdog timer expires.

Name Description
none Does not assert any of the trigger lines when the watchdog timer expires.
line 0 Asserts line 0 when the watchdog timer expires.
line 1 Asserts line 1 when the watchdog timer expires.
line 2 Asserts line 2 when the watchdog timer expires.
line 3 Asserts line 3 when the watchdog timer expires.
line 4 Asserts line 4 when the watchdog timer expires.
line 5 Asserts line 5 when the watchdog timer expires.
line 6 Asserts line 6 when the watchdog timer expires.
line 7 Asserts line 7 when the watchdog timer expires.
SMB line 0 Asserts SMB line 0 when the watchdog timer expires.

Default: none

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disable watchdog on VI exit

Boolean value that specifies whether to disable the watchdog timer object when this node stops running.

True Disables the watchdog timer object when this node stops running.
False Does not disable the watchdog timer object when this node stops running.

Default: True

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error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

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watchdog ID

ID of the watchdog timer object.

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actual timeout

Actual time in seconds that the watchdog timer will wait before it expires.

actual timeout equals desired timeout if the current target supports the value of desired timeout. Otherwise, actual timeout equals the next supported value that is greater than desired timeout.

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occurrence

Occurrence associated with the interrupt action that asserts when the watchdog timer expires.

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error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Creating Multiple Watchdog Timer Objects

A real-time target typically contains only one watchdog timer. However, you can create multiple watchdog timer objects and use one object at a time. If a watchdog timer object is running, you must use the Watchdog Timer Clear node to close the watchdog timer object before you can use another one.

Use this node to create multiple watchdog timer objects with separate configurations for applications that include distinct states of operation with different timing characteristics. For example, if you implement a state machine architecture with states A and B, you can use a watchdog timer object with a timeout value of 5 seconds in state A and another watchdog timer object with a timeout value of 10 seconds in state B.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application


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