RPM Signal for CSU Prop

So here are 2 images.  The instrument itself that displays the RPM, and the wiring diagram. Note the mention of 912/914 down the bottom.

But it doesn't say how to do this.  The instructions themselves are actually quite poor.  I think a lot has been lost during the french to english translation. 

Speculating: Why not connect the CS Controller RPM wire, to the same wire that gives your Garmin its engine RPM information?

Can I do that though?  I have read on another site, that it's probably not possible. They said you can't run 2 off the same wire.

I would need to find that wire - Although should be easier I guess.  Just need to make sure it's doable.

Speculation again: The RPM signal is a short duration low power(?) pulse. Splicing a second wire onto it, should have little or no detrimental effect on the "signal"

Hi John, Several years ago I tried splicing into my Rotax 914 rpm signal with a CSU box something like yours and had a lot of problems which remained unsolvable despite the manufacturer’s advice.  Several times the signal caused the prop to go to full fine while cruising at 120 kts requiring a rapid pull up and power off to prevent over speeding the engine!  Not good but luckily I was flying solo at the time, imagine the effect on a passenger?  Eventually I gave the CSU away, initially reverting to just flying in Manual then changing to the Airmaster system which generates its own rpm with an independent prop sensor control.  You should read the problems with Aviasport rpm indicators which often relate to the erratic signals generated by the Rotax rpm system.  This could cause you grief like with mine.  Perhaps hopefully your CSU manufacturer has a less sensitive input setting?  Best of luck with it.