Time for The Watch Dog

Years ago I worked in an environment with heavy equipment, run by computers.  Very leading edge at the time, well as on the edge as big corporations can get.  It was entirely possible for the system to crash as all computer programs like to do.  For most of us real world users, this meant possibly a hours worth of work lost, more or less. Not life threatening.  At the time engineers recognized that there would be bugs, and life threatening or catastrophic damage was possible.  They devised (or borrowed) an elegant yet simple solution.  The “Watch Dog Timer”, this timer had ultimate control.  A simple count down timer had to be reset before a specific interval had passed.  If the timer ran out, implying that the computer was possible becoming unresponsive, then all control signals for live equipment were cleared, effectively stopping everything before bad things happened.

I find decades later I’m going to be doing the same with my Yardcam setup.  Several times this past Winter an inexplicable event has occurred.  My LTE Hotspot has stopped communicating with the cell phone network.  Past experiences have been limited, but the unit gets hung negotiating a connection with the local Cell Tower.  The unit will have 3-4 bars, 3G or 4G status, but no data moving.  Most annoying as it requires me to drive several hundred kilometers to press and hold the power button, turning it off.  Then I release the button.  Then I press again to turn it back on.  With in moments the unit has a functioning cell tower connection. Duh.   I’ve requested from my service provider at their end to effectively hang up on the LTE Hotspot, forcing the LTE to try again, but to no avail.

Recently I had a compound failure.  The computer serving as the host for the webcam decided to reboot.  Though I thought I’d turned off every possible avenue for that behaviour, I missed something.  The result is the image showing “No device selected”, a bug between the HP Netbook and the Logitech Webcam I’m using.  On an Acer Netbook its fine, the device is found after a reboot and selected.  The solution here, is of course to reselect the device.  Again Duh!  In future I’ll be able to do this with a Remote Desktop connection.  However can’t do that if the LTE Hotspot is broken, which it did about 4 days later.

This is where the Watch Dog Timer comes in.  I’m going to set it up to force a restart of the LTE Hotspot every X number of days.  How I’m going to do that, I don’t know, but I’ll figure out something.

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