Thanks HenrikOlsson for your information.But this look like is not clear to me. From what I now when stepcount1 =36 for 2nd phase then stepcount1=12 so as it start to the 12thbyte again because initially is declared as stepcount1=12.What confusing me is that initially in my declaration of variable stepcount1=12 why after one cylecle stepcount1 should declared as stepcount1=0.How can I archieve phase difference of 120 if stepcount=0 after one cylecle.