Always enable bit in ABB Codesys

[hema]

Do anyone knows always enable bit address in codesys software? ABB CPU is PS583.


Thanks !

 

[parky]

I don't know codesys, however, you can create one.
OR AlwaysOn
OR NOT AlwaysOn
= AlwaysOn.
In LAD

 

[Mara]

You can make your own like Parky already mentioned but there's even easier way.

Just create variable to global variable list like this : AlwaysOn :BOOL:=TRUE;

Now you can access to variable from the programs by typing <var.list name>.AlwaysOn

 

[Lare]

You can make your own like Parky already mentioned but there's even easier way.

Just create variable to global variable list like this : AlwaysOn :BOOL:=TRUE;

Now you can access to variable from the programs by typing <var.list name>.AlwaysOn

Is that initial value or value allways at global vars.
What happens if by mistake value is writed to false on ladder side?

 

[hema]

Thank you so much for Fast reply.
Like a system clock bits in siemens (m8000.2),do we have in ABB?


Note:No need to turn ON bit from user side,whenever CPU goes to run condition,automatically this bit(M8000.2) bit will ON.

 

[parky]

Looked on the website, as useful as a chocolate fire guard. I suggest you use one of the two already stated unless you can find the programming and hardware manuals. If you put the code in the first rung of the cyclic scan there should be no problems.

 

[AustralIan]

The keyword TRUE can be used as always enabled bit.

 

[AustralIan]

Or use a read only variable (constant)
VAR_GLOBAL CONSTANT
Always on : BOOL := TRUE;
END_VAR

Or local to the POU

VAR CONSTANT
Always on : BOOL := TRUE;
END_VAR

 

[hema]

Thank you so much !!!!

 

[Mara]

Is that initial value or value allways at global vars.
What happens if by mistake value is writed to false on ladder side?

You are absolutely right on this and i didn't thought it. Australian gave much better suggestion to this:

Or use a read only variable (constant)
VAR_GLOBAL CONSTANT
Always on : BOOL := TRUE;
END_VAR

Or local to the POU

VAR CONSTANT
Always on : BOOL := TRUE;
END_VAR