This blocks computes the scalar Real output "y" as sum of the elements of the Real input signal vector u:
y = k[1]*u[1] + k[2]*u[2] + ... k[N]*u[N];
The input connector is a vector of Real input signals. When a connection line is drawn, the dimension of the input vector is enlarged by one and the connection is automatically connected to this new free index (thanks to the connectorSizing annotation).
The usage is demonstrated, e.g., in example Modelica.Blocks.Examples.RealNetwork1.
If no connection to the input connector "u" is present, the output is set to zero: y=0.