Watchdog Timer Configure
- Updated2023-02-17
- 5 minute(s) read
Watchdog Timer Configure
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.
Inputs/Outputs
desired timeout
Time in seconds that you want the watchdog timer to wait before it expires.
Default value: 1 s
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.
expiration actions
Actions that the node takes when the watchdog timer expires.
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 value: False
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 value: False
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 value: False
trigger protocol
Protocol used for trigger action on the PXI bus when the watchdog timer expires.
| 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 value: active high
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.
| 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 value: none
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 value: True
error in
Error conditions that occur before this node runs.
The node responds to this input according to standard error behavior.
Default value: No error
watchdog ID
ID of the watchdog timer object.
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.
occurrence
Occurrence associated with the interrupt action that asserts when the watchdog timer expires.
error out
Error information.
The node produces this output according to standard error behavior.
Programming Patterns
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.