Hi Thomas,
Starting in January 2015 I have had 3 individuals report their tachometer reports "0000" regardless of where it is set (side note: the tachometer kit code is different than the posted Arduino code.. I improved upon it). All three of these individuals had SX2P mills
One of these individuals was kind enough to connect an arduino with the posted arduino test code to allow me to view what the samples looked like. Unfortunately it seems as if Sieg industries has completely changed their protocol!
I am confident that I will be able to make updates to make the arduino code and my tachometer kits work but in order to do this I really need someone to probe the units with a logic analyzer and provide me with the dump of that. Do you happen to own one?
While a significantly greater hassle, this should be possible to diagnose on an Arduino too with a sufficient number of samples. Currently I'm not sure if the size of each "frame" has increased in side and consequently led to me not seeing the whole picture.
I would be happy to walk you through these processes if you are interested in helping. I do have someone else who is willing to help but they have other interests and I don't want to tie up all of their time figuring this out if they do not enjoy it.