Specify the direct feedthrough status of a block's ports
void ssSetInputPortDirectFeedThrough(SimStruct *S, int_T port, int_T dirFeed)
SSimStruct representing an S-Function block.
portIndex of the input port whose direct feedthrough property is being set.
dirFeedDirect feedthrough status of the block specified by
port.
Use in mdlInitializeSizes or
mdlSetWorkWidths (after
ssSetNumInputPorts) to specify the direct feedthrough (0 or 1)
for each input port index. If not specified, the default direct feedthrough is 0.
Setting direct feedthrough to 0 for an input port is equivalent to saying that the
corresponding input port signal is not used in mdlOutputs or
mdlGetTimeOfNextVarHit. If it is used, you might or might not
see a delay of one simulation step in the input signal. This might cause the
simulation solver to issue an error due to simulation inconsistencies.
Note
The ssSetInputPortDirectFeedThrough macro becomes a
function when you compile your S-function in debug mode (mex
-g).
C, C++
See the S-function sfun_dtype_io.c used in sfcndemo_dtype_io and the S-function sdotproduct.c used in sfcndemo_sdotproduct.