Is this "impossible" or "normal"?

[perion]

I've been told the following was "impossible" by some experts and "normal" by others. But it does happen (sometimes). So is it normal???

An irb6600 controlled with an s4c+ has a motion supervision error sometimes when poking a piston+liner into an engine block. This is normal if the humans forgot to lube some o-rings thru which the liner passes. The weird thing is that sometimes (maybe one out of four), instead of the PP being located on the MoveL where the "crash" occured, it is located several instructions on down in the routine. The PP actually has jumped past a whole bunch of gripper and move instructions as if it had executed them. But, positionally, it hasn't come close to even completeing the particular MoveL, let alone any of the gripper and move instructions that follow.

Any insights?

Here's where it happens in the prog code (see below): Motion supervision fault occurs at 1, PP then seen skipped down to 2

    !
1 MoveL Offs(pLd13LSleeve_1,0,0,20),v200,z10,toolGrip;
    MotionSup\On\TuneValue:=200;
    MoveL pLd13LSleeve_1,v100,fine,toolGrip;
    !
    rGripper (OPEN_SLEEVE);
    !
    TPWriteStat " Loading 13 Liter Cap..."\Animate;
    ![/size]
    MotionSup\On\TuneValue:=100;
    AccSet 100,100;
    !
    MoveL Offs(pLd13LSleeve_1,0,0,100),v500,z10,toolGrip;
    MoveL Offs(pLd13LSleeve_1,0,0,250),v1000,z100,toolGrip;
    MoveJ Offs(pLd13LCap_1,0,0,250),v1000,z100,toolGrip;
    MoveL Offs(pLd13LCap_1,0,0,20),v500,z10,toolGrip;
    MoveL pLd13LCap_1,v200,fine,toolGrip;
    !
2  rGripper (OPEN_13CAP);
    !
   
ut1880h

[cezanne]

I think it is impossible, the program is executed ahead of robot motion, but the cursor has to wait in the 3rd line because the zone is defined as fine. If you have a fine point the execution will not continue until the robot has reached the exact point.

 !
1 MoveL Offs(pLd13LSleeve_1,0,0,20),v200,z10,toolGrip;
    MotionSup\On\TuneValue:=200;
3 MoveL pLd13LSleeve_1,v100,fine,toolGrip;
    !
    rGripper (OPEN_SLEEVE);
    !
    TPWriteStat " Loading 13 Liter Cap..."\Animate;
    ![/size]
    MotionSup\On\TuneValue:=100;
    AccSet 100,100;
    !
    MoveL Offs(pLd13LSleeve_1,0,0,100),v500,z10,toolGrip;
    MoveL Offs(pLd13LSleeve_1,0,0,250),v1000,z100,toolGrip;
    MoveJ Offs(pLd13LCap_1,0,0,250),v1000,z100,toolGrip;
    MoveL Offs(pLd13LCap_1,0,0,20),v500,z10,toolGrip;
    MoveL pLd13LCap_1,v200,fine,toolGrip;
    !
2  rGripper (OPEN_13CAP);
    !