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TargetLink Data Types Application Note September 2004

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A subsystem is converted to TargetLink. Inside the subsystem is a

Simulink Gain block whose output signal type is specified to be

uint16

. Consequently, the output data type (

output.type

) property of

the replacing TargetLink block is set to

UInt16

, and this type is used

during production code generation. However, the TargetLink Gain

block will not simulate

uint16

using integer arithmetic, but will

produce doubles. This applies even if the Gain block’s input signal has

an integer data type. During MIL simulation, the output is checked for

compliance with the

UInt16

range (overflow detection).

This has two consequences:

■ When integer data types are involved, the simulation behavior may

be different after conversion.

■ Since signal data types have changed, conversion might introduce

data type conflicts, which makes simulation after conversion

impossible without additional manual work, i.e. insertion of

DataTypeConversion

blocks.

The latter could be the case if, for example, the Gain block’s output is

fed to another block outside the converted subsystem, whose input is

required to be

uint16

. After conversion, the Gain block’s output is

double, so the model cannot be initialized.

Evaluation of Simulink Data Types

During conversion, Simulink data types of block outputs are evaluated

and used when the data types (

output.type

property) of the replacing

TargetLink blocks are set. Two approaches to evaluating Simulink data

types have been implemented, as described below.

Compiled Scaling Parameters

During conversion, a model can be set to the so-called compiled

mode. In this mode, the data types and scaling parameters of all

signals (block outputs) can be read out using the Simulink API.

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