Lenze PLC Designer PLC Designer (R2-x) Instrukcja Użytkownika Pobierz pdf (Strona 531)

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L-force | PLC Designer

Data types in PLC Designer

 DMS 3.2 EN 02/2011 TD29 529

Example:

In the case of a variable belonging to a signed subrange type (like i, above), the

function CheckRangeSigned is called; it could be programmed as follows to trim a

value to the permissible range:

FUNCTION CheckRangeSigned : DINT

VAR_INPUT

value, lower, upper: DINT;

END_VAR

IF (value < lower) THEN

CheckRangeSigned := lower;

ELSIF(value > upper) THEN

CheckRangeSigned := upper;

ELSE

CheckRangeSigned := value;

END_IF

In calling up the function automatically, the function name CheckRangeSigned is

obligatory, as is the interface specification: return value and three parameters of type

DINT

When called, the function is parameterized as follows:

• value: the value to be assigned to the range type

• lower: the lower boundary of the range

• upper: the upper boundary of the range

• Return value: this is the value that is actually assigned to the range type

An assignment i:=10*y implicitly produces the following in this example:

i := CheckRangeSigned(10*y, -4095, 4095);

Even if y for example has the value 1000, then i still has only the value 4095 after this

assignment.

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