The below example from the Scripting Index illustrates the syntax to use to read in the limits each time the Control Chart is run. If the limits change in the limits table between runs, the control limits when change in the new chart.
Names Default To Here( 1 );
dt = Open( "$SAMPLE_DATA/Quality Control/Coating.jmp" );
obj = dt << Control Chart(
Sample Size( :Sample ),
Chart Col( :Weight, XBar, R ),
Get Limits( "$SAMPLE_DATA/Quality Control/CoatingLimits.jmp" )
);
Jim