This information is part of the Modelica Standard Library maintained by the Modelica Association.

This blocks defines the transfer function between the input u and the output y as second order system:

                    k
y = --------------------------------- * u
     ( s / w )^2 + 2*D*( s / w ) + 1

If you would like to be able to change easily between different transfer functions (FirstOrder, SecondOrder, ... ) by changing parameters, use the general model class TransferFunction instead and model a second order SISO system with parameters
b = {k}, a = {1/w^2, 2*D/w, 1}.

Example:

   parameter: k =  0.3,  w = 0.5,  D = 0.4
   results in:
                  0.3
      y = ------------------- * u
          4.0 s^2 + 1.6 s + 1

k	Value: 1 Type: Real Description: Gain
w	Value: Type: Real Description: Angular frequency
D	Value: Type: Real Description: Damping
initType	Value: Init.NoInit Type: Init Description: Type of initialization (1: no init, 2: steady state, 3/4: initial output)
y_start	Value: 0 Type: Real Description: Initial or guess value of output (= state)
yd_start	Value: 0 Type: Real Description: Initial or guess value of derivative of output (= state)

yd	Type: Real Description: Derivative of y