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...)

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"})

Is DOT essentially doing a 3D Distance? And would you do that function first or after the MININDEX where the generic point is PNT1?

The dot product is going to give the distance from a point to a plane that lies at the origin perpendicular to a vector. The plane in this case will be parallel to PLN1. Subtracting that distance from the distance of the point to the perpendicular plane leaves the distance between the point and the plane only in that direction. It is a 2d distance that lies in a plane perpendicular to PLN1 and through PNT1. You would calculate distances with the function and then find the smallest or largest depending on the application. This is how you find distance of points from a plane even if the plane is not square to an axis.

You can level to the plane, set an origin, and then check axis values. You should get the same numbers. You could also construct a 3d line perpendicular to the plane and through the point, create an intersection point with the line and plane, and check the 3d straight line distance between points.

All of them are viable solutions. I just find the mathematical methods to be easier to understand what a program is doing when reading through it offline, rather than a bunch of "measure, measure, construct, construct, report" etc.