Retentive Bool Parameter

Hi,

I would like to know the best way to keep a bool parameter in high state in case of a power failure or simply when you turn the controller off and then turn it back on.

I will connect a Logo! to an HMI, then I am going to set a flag from the HMI either on or off according to the requirements. I’m afraid that if I set the flag on and the power fails (which happens quite frequently) then when the power comes back on the flag will lose its on state.

I came up with the attached circuit, will it work?

Can you point me to a good solution if it has been discussed before?

Thank you

P.S. Please, excuse me if this a basic question, I’m still new to Logo!

Re-uploaded

Now it can be seen without scrolling

I need no set a memory block from the HMI and want it to retain the value when I switch the controller off or a power failure occurs.

I know memories are not retentive, I'm looking for a way to change it from the HMI and make it retentive

Thank you

No, not at all. Just what I wrote, I want to change a bit from the HMI and it must keep its state in case of a power failure

Thank you

I do know the retentive function, memories are not retentive but softkeys are, on the other hand you can change the state of a memory from the HMI but you cannot change softkey's state from the HMI (as far as I know)

Again, if I change a memory value to "hi" and after that I turn the power off, the memory will be "lo" the next time I switch the power on.

Hope it is clear now

Thank you