Formula Atrribute

Hi,

I have Cable name "-W4401" of Type Multi-Core Cable in Equipment system folder In EBase.. There are many wire as child node for the cable. Some of the wire has Destination 1 and Destination 2 attribute but some of then not has. Means that some of the wire is used and some of them is spare. I want to add two Formula attribute on Cable (Multi-Core Cable ) level so One will tell number of used wire count and Other will tell number of unused wire count in all child wire.

I tried some of formula but could not get desire result. e,g

R-3;{=r1d+K1A294;{="" "1";}{:"" "0";}};=R1;

Please help me create formula for mention requirement

Thanks
Neeraj Kumar