PXI Hardware Watchdog

The RT Series PXI Controller is equipped with a hardware feature that alerts the user when a certain event occurs. Similar to the Software Watchdog concept, the PXI Hardware Watchdog monitors the status of an on-going hardware or software process. The PXI Hardware Watchdog can be used to detect when a VI running on the PXI controller has "died," or even when an external process has stopped responding to the PXI controller. Unlike the Software Watchdog concept, which involved writing to shared memory, using a digital I/O line, or a counter/timer on the DAQ daughterboard, the PXI Hardware Watchdog is actually a built-in dedicated counter/timer on the PXI controller that the user has access to via the PXI Watchdog VIs.


The PXI Hardware Watchdog has a timeout period that the user configures with Watchdog Configure.vi. The Hardware Watchdog then performs a predefined action when the timeout period expires. These action options are resetting the PXI controller, setting an occurrence (interrupt) in LabVIEW RT, or asserting a trigger line on the PXI hardware. To prevent the Watchdog from timing out, the process being monitored can "whack the dog" by calling Watchdog Whack.vi, which essentially resets the counter/timer on the PXI controller. On the other hand, if the process stops running, then it can no longer call Watchdog Whack.vi, so the Watchdog will eventually timeout.

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