Xy Graph x,y value programmatically change

Hi,

     i  am using labview 8.2.want set x,y value programattically.for example i will give x min value 6(clock) and max 10(clock),interval 30min.so 6:00,630,7:00,7:30.....up to 10:00 how to set this type.i tryed using property node min and max property but this not give correct output