Memory or Data Block? Function or Function Block?

koaladua · Feb 11, 2013

Hi,

I am still confused when to use just simple memory tags or put it in a data block. The same, when to put your ladder logic in a function or a function block.

Can anyone shed some light on this please? Thanks.

shooter · Feb 11, 2013

siemens uses datablocks but codesys just uses markers.

ladder logic can only be put in a function when the result is only one bit
otherwise you have to use blocks
with me all safeties are in ladderlogic and in separate program. (this way i can easier simulate and as a ladder is always from begin to end (when no jumps are used) it is safe.

L D[AR2P#0.0] · Feb 11, 2013

If you can fit all of the variables you wish to use in the M bits available for your CPU (noting the rententive capabilities for M bts for your CPU), then you don't need to use global DBs.

Functions should be used to process a set of inputs and provide a return value.

Function blocks should be used for everything else.

koaladua · Feb 11, 2013

Thanks

L D[AR2 said:
If you can fit all of the variables you wish to use in the M bits available for your CPU (noting the rententive capabilities for M bts for your CPU), then you don't need to use global DBs.

Functions should be used to process a set of inputs and provide a return value.

Function blocks should be used for everything else.

shooter said:
siemens uses datablocks but codesys just uses markers.

ladder logic can only be put in a function when the result is only one bit
otherwise you have to use blocks
with me all safeties are in ladderlogic and in separate program. (this way i can easier simulate and as a ladder is always from begin to end (when no jumps are used) it is safe.

Thank you very much for the replies. Now I begin to understand it.

Cheers.

Memory or Data Block? Function or Function Block?

koaladua

Member

shooter

Member

L D[AR2P#0.0]

Lifetime Supporting Member

koaladua

Member

Similar Topics