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Reply to "Proposed Solution to DCS Watchdog in Yard Tracks (DCS-RC WD Gerber Files Added to First Post)"

I realize this is over the top but I'll document it here anyway for future reference.  This is a refinement to my initial idea of a cycling relay to perpetually turn on/off a DCSRC once per second.  This would generate a DCS watchdog signal that would always be available to a yard siding or round-table spoke that was turned on with track power from an already active TIU output channel (so no watchdog).

The refinement was to recognize that the DCSRC uses a microprocessor chip inside.  And virtually all microprocessor chips have a signal input that will reset/restart/reboot the program.  So rather than an electro-mechanical relay perpetually clicking, why not generate an electronic signal to reset the microprocessor once per second.   Without getting into arcane details, the relevant signals in the DCSRC are conveniently available on a connector.  So by simply installing 3 pin on this connector, a circuit can be added which resets the processor chip once per second.

The 3 pins are +5V, Ground, and the Reset signal.  The 5V circuit is about $1 in readily available commodity parts and generates a narrow pulse about once per second which then resets the processor chip once per second.  The DCSRC appears to generate the watchdog about 3/4 sec after a reset.  Note that the modification is "additive" in that signal traces or components on the DCSRC itself are not modified, removed, etc.  So simply popping off the circuit board restores the DCSRC to its native function.

Perpetual watchdog generator using a DCSRC

And here it is in action.

The green LED on the DCSRC briefly blinks off on each reset but it does not show up in the video.  The video shows track power with a perpetual watchdog (provided by the modified DCSRC) applied to a track with a PS2 engine; you can see the lock-on light turn on and hear the engine's relay click on when power is applied.  In each case the engine starts up silent (in command mode).  Then the perpetual watchdog is remove.  Now when power is applied the engine starts up in conventional since there's no watchdog.  And in this example, the engine happened to be locked in conventional forward so it starts moving illustrating the undesirable scenario described earlier and in other threads.

So now the configuration would be:

dcs perpetual watchdog generator

So this is just another alternative to the methods already described.

It is surely more complicated to implement though arguably easier for the end-user to operate.  Like comparing manual vs. automatic transmission, the clutch is an added step for the end-user.  The automatic transmission makes it easier for the end-user but is a more complex mechanism.  I compare the clutch to the extra step of toggling an extra on-off switch to cycle power to the TIU/DCSRC or having to first return the rotary switch to the home/off position. 

 

 

 

 

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