Thanks - I can;t get that to work.
I think the difficulty I am running into is that I am not getting a result from the binary but rather the index of the fist 1 within the binary list. This is coming from a plugin in the repeating group so the data is not saved in the database but dynamic on the page which is why i thought custom states may be the answer. My next approach is to write the index value to the database on value change but this may cause performance issues.