Check variable status periodically of Matlab Function Block input

Hi every one.

I'm working with this system:

Vector "Constant2" contains 122 bits (122 0s or 1s), Serializer1D Block changes parallel to serial (sends one by one bit), Delay Block delays the bitstream (in this case 1 us).

Bellow an example with 50 us delay:

In the MATLAB Function BITS COUNTER I need to check u input periodically, in order to get what bit is there (one or zero) and obtain a bit count. Check Period must be determined by me, but that is the problem, I don't know how to implement that kind of code.

Could someone give me some advice or recommendation?

Regards

William