Need for Watchdog Timers in a Packaging Application
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This document is part of a comprehensive tutorial on industrial Digital I/O and Counter/Timer hardware. Learn about National Instruments product offerings for digital and timing I/O, the Industrial Feature Set including watchdog timers and isolation, complementary devices like relays, solenoids and encoders, concepts like sinking and sourcing, and see how these devices can be used in your industrial application.
For more information return to the Complete Industrial Digital I/O and Timing Tutorial
Table of Contents
Need for Watchdog Timers in a Packaging Application
Bubble gum is cut and packaged at a candy factory. A blade slices the gum into pieces, and a conveyer moves the pieces into a packaging machine. Both the blade and the conveyer are controller by digital output lines. If the control application hangs, the conveyer would ideally stop moving and the blade would be moved away from the gum. Otherwise, machinery could be damaged, and gum could be needlessly wasted. Digital I/O watchdogs provide a way to set the outputs of a digital board to known safe states in the event of a system fault or failure. The digital I/O board constantly receives confirmation that the computer is still functioning properly. If this confirmation is not received within a programmable timeout, the safe states are written to the outputs.
Recommended Products that Feature Watchdog Timers
NI 6509
NI 6514
NI 6515
NI 6528
Learn More About Watchdog Timers
The Industrial Feature Set: Watchdog Timers
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