S-Function Block- Create Mask Error

I drag and drop the "S-Function" block in a new Simulink library, and then right click on the block and choose Create Mask.

A Mask Editor windows is displayed, in the Icon Drawing commands, I would like to have two input ports, for example below.

port_label('input', 1, 'Time'); port_label('input', 2, 'Event');

the block shows three question signs, it only allow me to have one port.

I am using MATLAB 2011b.

Answer 1

[Kaustubha Govind]

Which S-function did you select for the block? There needs to be a C-MEX or MATLAB-file S-function associated with it. That S-function needs to be configured to accept two ports. In C-MEX S-functions, you can use ssSetNumInputPorts in mdlInitializeSizes and in MATLAB S-functions, you can use block.NumInputPorts in the setup function.