Set initial value continuous state in S-function based on an externally defined value

Hey,

I am trying to make an S-function to solve a system of ODEs, so I want to give an initial value to the continuous states to implement the initial conditions. I have given the vector of intial values as an input to the S-function, however in the Start method I can not read the value of the InputPort yet, or atleast it is still set to 0. How do I implement an intial value to a continuous state based on an externally defined value?

I tried to do the following in the Start method, however as I mentioned, all the InputPorts are still set to 0 when this method is called.

function Start(block)
N = block.NumContStates/3;

block.ContStates.Data(1:N) = block.InputPort(4).Data;                                           % initial density
block.ContStates.Data((N+1):(2*N)) = block.InputPort(4).Data .* block.InputPort(5).Data;        % intial phi = density*local flow velocity
block.ContStates.Data((2*N+1):(3*N)) = block.InputPort(4).Data .* block.InputPort(6).Data;      % initial alpha = density*stagnation interal energy
%end Start

Thank you very much!