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Document Type: Example Program
NI Supported: Yes
Publish Date: Sep 6, 2006

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Using a Watchdog Timer to Disable Critical Systems During a Software Failure

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Filename: watchdog.zip
Requirements: View

This example creates a watchdog timer using the NI-DAQ 6.5.x LabVIEW counter VIs. This VI works with only DAQ-STC and NI-TIO based counter devices. Watchdog timers are used to disable critical systems in the event of a software failure, such as a software hang, operating system crash, major virus attack, and so on.

Use watchdog timers for critical applications that must be under software control at all times to prevent dangerous or unwanted circumstances. The main part of a watchdog timer is a software command to generate a delayed TTL pulse or toggle. The software is required to regularly reset the watchdog timer. If the timer is reset within the delay period, the pulse is never generated. However, if the pulse is not reset due to a software failure (or any other reason), the delay expires and the TTL signal is generated. You can use this signal to control a relay or other such circuitry that would shut down the critical equipment.

Requirements


Filename: watchdog.zip

Software Requirements


Application Software: LabVIEW Full Development System 5.1
Language(s): LabVIEW

Hardware Requirements


Hardware Group: Multifunction DAQ (MIO)
Driver: Traditional NI-DAQ (Legacy) 6.5.0

 
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This example program (this "program") was developed by a National Instruments ("NI") Applications Engineer. Although technical support of this program may be made available by National Instruments, this program may not be completely tested and verified, and NI does not guarantee its quality in any way or that NI will continue to support this program with each new revision of related products and drivers. THIS EXAMPLE PROGRAM IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND AND SUBJECT TO CERTAIN RESTRICTIONS AS MORE SPECIFICALLY SET FORTH IN NI.COM'S TERMS OF USE (http://ni.com/legal/termsofuse/unitedstates/us/).