mdlSetInputPortSampleTime (Writing S-Functions)

Set the sample time of an input port that inherits its sample time from the port to which it is connected.

Syntax

void mdlSetInputPortSampleTime(SimStruct *S, int_T port, 
real_T sampleTime, real_T offsetTime)

Arguments

S
SimStruct representing an S-Function block.

port
Index of a port.

sampleTime
Inherited sample time for port.

offsetTime
Inherited offset time for port.

Description

Simulink invokes this method with the sample time that port inherits from the port to which it is connected. If the inherited sample time is acceptable, this method should set the sample time of port to the inherited time, using ssSetInputPortSampleTime. If the sample time is unacceptable, this method should generate an error via ssSetErrorStatus. Note that any other inherited input or output ports whose sample times are implicitly defined by virtue of knowing the sample time of the given port can also have their sample times set via calls to ssSetInputPortSampleTime or ssSetOutputPortSampleTime.

When inherited port-based sample times are specified, the sample time is guaranteed to be one of the following.

Sample Time
Offset Time

Continuous
0.0
0.0

Discrete
period
offset

	Sample Time	Offset Time
Continuous	`0.0`	`0.0`
Discrete	`period`	`offset`

where 0.0 < period < inf and 0.0 <= offset < period. Constant, triggered, and variable step sample times are not propagated to S-functions with port- based sample times.

Generally mdlSetInputPortSampleTime is called once with the input port sample time. However, there can be cases where this function is called more than once. This happens when the simulation engine is converting continuous sample times to continuous but fixed in minor steps sample times. When this occurs, the original values of the sample times specified in mdlInitializeSizes are restored before this method is called again.

The final sample time specified at the port can be different from (but equivalent to) the sample time specified by this method. This occurs when:

The model uses a fixed-step solver and the port has a continuous but fixed in minor step sample time. In this case, Simulink converts the sample time to the fundamental sample time for the model.

Simulink adjusts the sample time to be as numerically sound as possible. For example, Simulink converts [0.2499999999999, 0] to [0.25, 0].

The S-function can examine the final sample times in mdlInitializeSampleTimes.

Languages

mdlSetInputPortFrameData mdlSetInputPortWidth