How to find the minimum coordinate in a plane

Post the code for the planes and the dimension.

Sorry! here it is:

MOVIM/PIANOSICUREZZA
PIANO1_1   =ELEM/CONTATTO/PIANO/PREDEFINITO,CARTESIANO,NESSUNO,MIN_QUAD
            TEOR/<0,-0.002,0>,<0,0,1>
            REALE/<0.008,0.007,0.025>,<-0.0000557,-0.0000271,1>
            DEST/<0,-0.002,0>,<0,0,1>
            VETT ANGOLO=<1,0,0>,RADIALE
            MOSTRA PARAMETRI ELEMENTI=NO
            MOSTRA PARAMETRI CONTATTO=SÌ
              NUM PUNTI=3,NUM RIGHE=1
              DISTANZ=165
              MOVIM QUOTA=ENTRAMBI,DISTANZA=12
            MOSTRA PUNTI=NO
PIANO2_2   =ELEM/CONTATTO/PIANO/PREDEFINITO,CARTESIANO,NESSUNO,MIN_QUAD
            TEOR/<0,0,11>,<0,0,1>
            REALE/<-0.004,0.001,10.816>,<0.0029128,-0.0011073,0.9999951>
            DEST/<0,0,11>,<0,0,1>
            VETT ANGOLO=<0,1,0>,RADIALE
            MOSTRA PARAMETRI ELEMENTI=NO
            MOSTRA PARAMETRI CONTATTO=SÌ
              NUM PUNTI=10,NUM RIGHE=1
              DISTANZ=68
              MOVIM QUOTA=ENTRAMBI,DISTANZA=5
            MOSTRA PUNTI=NO
            MOVIM/PIANOSICUREZZA
DIM DIST5= DISTANZA 2D DA PIANO PIANO2_2 SU PIANO PIANO1_1 PAR SU   ASSEZ,NO RAGGIO  UNITÀ=MM,$
GRAFICO=OFF  TESTO=OFF  MULT=10.00  OUTPUT=ENTRAMBI
AS   NOMINALE       +TOL       -TOL        MIS        DEV   FUORITOL
M       11.000      0.200     -0.200     10.816     -0.184      0.000 #--------

as previously said...the quote 11 in some points is equal to 10.5 or 10.4 for sure.

I level Z+ over "Piano1_1"

let me know if the code is enough (It's my first time...)

How large is the surface? Do you need to get the entire face? You can do a UV scan for something like this with a larger surface. Smaller surfaces perimeter or linear open might work

Then put the points into a minindex expression in an assign statement, and put it into a generic feature if you need to report it

            ASSIGN/V1=MININDEX(SCN1.HITS.Z)
F1         =GENERIC/POINT,DEPENDENT,CARTESIAN,$
            NOM/XYZ,<0,0,0>,$
            MEAS/XYZ,<SCN1.HIT[V1].X,SCN1.HIT[V1].Y,SCN1.HIT[V1].Z>,$
            NOM/IJK,<0,0,1>,$
            MEAS/IJK,<0,0,1>

You should use a 3D-distance when it is distance between planes.

Easiest would be to align on one of the planes and then check the min distance for each point in the direction/axis you are interested in.

how can I check the min distance? I tried 3D+"the shortest" flagged, but the value is the same

It seams that UV scan requires the 3D model...and I don't have it

You can take those points you have on your surface and put all those points into a Constructed Set. Then do the MININDEX of that constructed Set. Add more points through out if needed.

I'm sorry but I'm really new on PC-Dmis...where can I find "Constructed Set" and "MININDEX"? can You screen these comands?

I'd be really glad!

Meanwhile I'm trying to find instructions from the F1 helpcenter of my PC-Dmis.

Insert > Feature > Constructed > Set, select all your points and create.

MININDEX is part of assign statement. Start typing "Assign" in edit window and after the =  put MININDEX(SCN1.HITS.Z)

If you're level to the plane, otherwise you'll have to check perpendicular distance to the plane.

ASSIGN/L=FUNCTION((PLN,PNT),DOT(PLN.IJK,PNT.XYZ)-DOT(PLN.IJK,PLN.XYZ))
ASSIGN/PD=L({"PLN1"},{"PNT1"})