@dc42 good news - Wired up my 2nd extruder - and this time I connected the Inductive Z probe ( 24V, 2.27V output) to the Filament Monitor 3.3v compliant connection IO1.in - and it seems to trigger ok.
So I think that is the solution unless I decide to add filament monitors. So thanks for your help.
Next issue is work out is how to handle 4 different Inductive Probes, a Switch Type Touch probe plus a positioning probe.
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