Hi, everyone,

I have a function block with 3 inputs (IN1,IN2,IN3), but sometimes I call the function just with input of IN1, or IN2?

For example: FB(IN1:=XX) or FB(IN2:=XX) or FB(IN1:=XX,IN2:=XX) etc.

How can I know which input is assigned when the function block is called?

Many thanks,

you cannot, because the variables stay in memory and the value is going to be what it was the last time.

i was looking for something like this and my solution was the following:

1. a default value outside the range of a normal value would show that the variable had not been set. this input value could then be overwritten anytime the function is called and you would know if the input was assigned or not.

for example: and input in1 with the range of 0..100 as value range

the function block itself has to make sure the input is always at a value outside the defined input range then it can decide if the input valkue has been set or not

var_input

in1 : real;

end_var

in in1 <= 100 then

input := in1

end_if;

in1 := 99999;