equation and function setup in Simscape

Hi, I need your small help. Lets say, I have I = C * dv/dt

which is:

dv/dt = I/C

If I integrate this equ, I will have

v = (I/C)*t + constant

where constant = v(t=0)

So, in simscape when I do:

function setup v = { 5 ,'V'}; end

equation i == C*v.der end

does this v(t=0) value is taken from function setup?

Or equivalently, does this mean:

v = (I/C)*t + 5

when I actually implement this simscape equ.

Please kindly let me know about "der" and "function setup" thing. I have read the manual and other stuffs in the Internet but I could not get my answer. I need to know how the initial value can be given in the equation using ".der"

Thanks