How to restrict entries per set. (i.e) Only one trade should be executed per Set

I have created a multi entry strategy with a total of 10 buy orders per day. and since it is a 15 minute breakout strategy i have created 10 sets for each entry. The problem is, if the first two 15 minutes ORB dont have any trades, then the 3rd 15 minute ORB gets 3 entries.
I used Position Details
Entry, B, ALL, BANKNIFTY <= 50.

I want the Set to Take only one entry per 15 minutes. (or) only one entry per set irrespective of previous number of trades.
Please help