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Section 1 Specifications
<Uses of input/output variables of a function block>
Use
Within a function block
Outside a function block
Read an input variable
Possible
Not possible
Write an input variable
Not possible
Possible
Read an output variable
Possible
Possible
Write an output variable
Possible
Not possible
Notes:
1) OUT retains the old value when it is called the next time.
2) Instances of the same FB do not affect each other if they are of different types.
3) Program
A program is the basic program organization unit for a user application. Only programs can be assigned to tasks (neither
functions nor function blocks can be assigned to a task). A program has neither input variables nor output variables.
PG
VAR
A_1:AAA;
A_2:AAA;
A:INT;
B:INT;
C:INT;
D:INT;
END_VAR
VAR_INPUT
IN:INT;
END_VAR
VAR_OUTPUT
OUT:INT;
END_VAR
A_1(IN:=B);
A:=A_1.OUT;
A_2(IN:=D);
C:=A_2.OUT;
FB
FB name: AAA
VAR_INPUT
IN:INT;
END_VAR
VAR_OUTPUT
OUT:INT;
END_VAR
OUT:=OUT+IN;
RET
Instance name: A_1
VAR_INPUT
IN:INT;
END_VAR
VAR_OUTPUT
OUT:INT;
END_VAR
Instance name: A_2
