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DAQmx Create Watchdog Timer Task (G Dataflow)

Last Modified: May 7, 2018

Creates and configures a task that controls the watchdog timer of a device. The timer activates when you start the task.

Use the digital physical channel expiration states input to set expiration states for digital channels. If your device supports expiration states for other channel types, use DAQmx Configure Watchdog Expiration States to configure those channels' expiration states. This node does not program the watchdog timer on a real-time controller. Use Real-Time Watchdog to program the watchdog timer on a real-time controller.

The DAQmx Watchdog properties contain additional watchdog timer configuration options.

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device in

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.

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timeout

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

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error in

error in describes error conditions that occur before this node runs. This input provides standard 'error in' functionality.

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digital physical channel expiration states

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.

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physical channels

physical channels 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 DAQmx Flatten Channel String to convert the array to a list.

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expiration state

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

Name Description
High

High logic.

Low

Low logic.

No Change

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

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.

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auto cleanup

auto cleanup specifies if the task is automatically destroyed when the application completes execution.

If auto cleanup is FALSE, the task is not automatically destroyed until you exit the application. Use DAQmx Clear Task to manually destroy the task.

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new task name

new task name is the name to assign to the task. If you use this node in a loop and specify a name for the task, you must use DAQmx Clear Task 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.

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task out

task out is a reference to the new task.

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error out

error out contains error information. If error in indicates that an error occurred before this node ran, error out contains the same error information. Otherwise, error out describes the error status that this node produces.

Where This Node Can Run:

Desktop OS: Windows

FPGA: LabVIEW NXG does not support FPGA devices

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


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