Rlo ?

RLO,

Result Of Logic Operation,

what is it, where can I find it, what can u do with it ?

In the Siemens S7 and, I believe, S5 PLCs, the RLO is a status bit that contains the instantaneous result of the logical operation just performed in a network. With the conditional exception of the first instruction in a network, the RLO is the other operand in the boolean operations. The first instruction in a network has an additional bit that makes sure that the status of the initial instruction carries through to the RLO.

You can see the result of the RLO if you view a network online in STL. The RLO is one of the columns in the status box. I'm not sure if you can access the RLO directly. However, any time you perform a boolean output from a network the RLO is what determines the status of the output bit. The conditional jump command also uses the RLO to deterine its action. There are other instructions that also use the RLO to trigger actions.

I hope I didn't confuse you more. The Step7 help contains some pretty good info on the RLO and how it reacts.

Keith

I hope

thanks

I understand,

I red about it in siemens books also,


thanks for you help

Hi guys,

I'm not a Siemens expert but I know that the RLO can be saved (like using a merker for a temporary result) to be used somewhere else in the program, I'm not sure but I do think that in can only be used in one rung.
Grtz