changing value

MAHER · Oct 4, 2014

Dear All,

i need your help in the below issue please:

i have a a variable value i need by using scl language to detect any changing in it according to the previous scan.

could you provide me by your ideas please.

thanks in advance.

Maher

cjd1965 · Oct 4, 2014

You need add a memory variable and compare the value now to the memory. If different do some action and then copy now value to the memory variable

MAHER · Oct 4, 2014

cjd1965 said:
You need add a memory variable and compare the value now to the memory. If different do some action and then copy now value to the memory variable

thanks a lot for your fast response,

could you clarify it more please.

Maher

nehpets · Oct 5, 2014

This is very generic and the syntax is Allen Bradly

if variable <> mem_variable then
output := 1;
mem_variable := variable;
else
output := 0;
end_if;

I'm not sure if this is what you are after?

Steve

MAHER · Oct 5, 2014

nehpets said:
This is very generic and the syntax is Allen Bradly

if variable <> mem_variable then
output := 1;
mem_variable := variable;
else
output := 0;
end_if;

I'm not sure if this is what you are after?

Steve

i tried this syntax but this is not working i know it should work but it is not working well.

i don't why

thanks in advance.

Maher

nehpets · Oct 5, 2014

it would help if you let us know which PLC or platform you are using, we could then work out the correct statement syntax.

Steve

MAHER · Oct 5, 2014

thanks you very much i realized where was my troubles,

because i am making detection for the time ( sec ) so the variation was created every sec so i got from the block a pulse.

thanks you very much.

Maher

changing value

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