second order ODE can be written as two first order ode's. So convert your second order ODE by introducting two state variables, x1(t) and x2(t). One for "position" and second for "speed".
Since you did not give an example of your second order ode's and its IC, I made one up.
ode := diff(x(t),t$2) +1/2*diff(x(t),t)+ x(t) = 0;
numpoints=200, linecolor=black, axes=boxed);