DAQmx Create Watchdog Timer Task

DAQmx - Data Acquisition VIs and Functions

DAQmx Create Watchdog Timer Task

Creates and configures a task that controls the watchdog timer of a device. The timer activates when you start the task. This VI does not program the watchdog timer on a real-time controller. Use the Real-Time Watchdog VIs to program the watchdog timer on a real-time controller.

The DAQmx Watchdog Timer properties contain additional watchdog timer configuration options.

DAQmx Create Watchdog Timer Taskc.gif

Place on the block diagram.

Find on the Functions palette.

device in is the name as configured in MAX of the device to which this operation applies. A DAQmx device name constant lists all devices installed in the system.

timeout is the amount of time in seconds until the watchdog timer expires. A value of -1 means the internal timer never expires. Set this input to -1 if you use an Expiration Trigger to expire the watchdog task. If this time elapses, the device sets the physical channels to the states you specify with the digital physical channel expiration states input.

Use the DAQmx Control Watchdog Task VI with the action input set to reset timer to prevent the watchdog timer from expiring.

error in describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. If an error occurs while this VI or function runs, the VI or function runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.

	status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.
	code is the error or warning code. The default is 0. If status is TRUE, code is a negative error code. If status is FALSE, code is 0 or a warning code.
	source identifies where an error occurred. The source string includes the name of the VI that produced the error, what inputs are in error, and how to eliminate the error.

new task name is the name to assign to the task. If you use this VI in a loop and specify a name for the task, you must use the DAQmx Clear Task VI within the loop after you are finished with the task. Otherwise, NI-DAQmx attempts to create multiple tasks with the same name, which results in an error. Refer to Task Creation and Destruction for more information.

auto cleanup specifies if LabVIEW automatically destroys the task when the application completes execution. If auto cleanup is FALSE, LabVIEW does not automatically destroy the task until you exit LabVIEW. Use the DAQmx Clear Task VI to manually destroy the task.

digital physical channel expiration states contains the states to which to set digital physical channels when the watchdog timer expires. Each element of the array contains a digital physical channel name and the corresponding state for that digital physical channel.

physical channel is the digital line or port to modify. You cannot modify dedicated digital input lines. The DAQmx physical channel constant lists all lines and ports for devices installed in the system. You also can wire a string that contains a list or range of digital lines or ports to this input. If you have an array of lines or ports, use the DAQmx Flatten Channel String VI to convert the array to a list.

expiration state specifies the state to which to set the digital physical channel when the watchdog timer expires.

High (10192)	High logic.
Low (10214)	Low logic.
No Change (10160)	Expiration does not affect the port. Do not change the state of any lines in the port, and do not lock the port. For example, if a line is high when the timer expires, that line stays high, and you can write new values to the line. You can select this value only for entire ports.
Tristate (10310)	High-impedance state. You can select this state only on devices with bidirectional ports, and you can select it only for entire ports. You cannot select this state for dedicated digital output lines.

task out is a reference to the new task.

error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, error out describes the error status that this VI or function produces. Right-click the error out indicator on the front panel and select Explain Error from the shortcut menu for more information about the error.

	status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
	code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
	source identifies where and why an error occurred. The source string includes the name of the VI that produced the error, what inputs are in error, and how to eliminate the error.

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