Technical DGT dash - tach

[sonoramicommando]

I have a spare DGT dash and thinking about using it for my other fiat (125).
From wiring diagram, it looks like getting the tach signal from DigiPlex2 - Does DigiPlex process the signal from the coil and convert into some different form, or is it unconditioned signal?

I have the speedo working using a sine wave generator but can't figure out the tacho.

cheers