I draw the graph like this, and then loop it once every minute. The requirement is that the vertical line of the X-axis can be changed according to the value of the specified variable
Thanks Experts!

a=26;
dt=Open("$SAMPLE_DATA/Big Class.jmp");
ca="r";New Column(ca);
p1=dt<< Graph Builder(
Variables( X( Transform Column( "Row", Formula( Row() ) ) ), Y( :height ) ),
Elements( Line( X, Y, Legend( 5 ) ) ),
SendToReport(
Dispatch(
{},
"Row",
ScaleBox,
{Add Ref Line( a, "Dotted", "Medium Light Red", "", 1 )}
)
)
);
While( 1,
a=Random Integer(1, 40);//Column(ca)<<Formula( if(row()==a,row()) );dt<<run formulas;Column(ca)<<deleteFormula;
Wait( 60 );
);