Emerson iPro SERIES Manuel d'utilisateur télécharger pdf (Page 39)

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Function blocks: they are a general routine (software) executed in different programs.

It is possible to “call” the FB in every part of the program; in this way is

not necessary to write the same program a lot of time. Besides you can

save them in the library and also protect them with a password.

These FB can be developed by ISaGRAF, Dixell and from third party.

Variables: they are values that can change during the execution of the program.

For each variable we can define:

• NAME: it is the name of the variable

• COMMENT: the description of the variable (free field)

• GROUP: you can organize the variables in different groups.

• INIT VALUE: it is the value when the program starts.

• TYPE:

Bool: can assume the value 0=FALSE, 1=TRUE

Dint: can assume values from -2147483648 to +2147483647

Real: can assume floating point values

String: contain character strings (with specified the length)

Time: contain values used in time expression

Any: function block

• DIMENSION: specifies the dimension of the array of variables

• RETAIN:

Yes: the value will be saved in not volatile memory

No: the value will not be saved

• ATTRIBUTE:

Read: the application can read the value but not change it

Write: the application can modify the value but not read it

Free: the application can read and modify the value

• DIRECTION:

Input: the application reads the value from field

Output: the application writes the value to the field

Internal: any other variables

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Emerson iPro SERIES Manuel d'utilisateur Page 39