Hi I couldn't find a similar topic so I made a new one.

In a ktp700 display is it possible to set the default state of a switch element as ON instead of OFF?

I made a LOGO! program that measures room temperatures gives alarms and it is connected to a ktp700 display. In the display I have networked switches that are used to turn of certain alarms.

Now the problem is that after a power failure all the switches turn OFF.

I read from other topics that in TIA portal it is not possible to set retentivity to these switches but if it is somehow possible to change the default state to ON, it would be fine too.

Or is there any other possibilities that I could use to overcome this problem?

Otherwise I have to use a ups backup battery for the plc.

 Hi 

Thanks for the quick reply. 

Ah yes. Of course. "all bits in VM memory are 0". This makes it clear for me.

Ok well thats unfortunate then. 

Yeah I quess a button connected to a pulse relay is the way to go then.

I just have to add some animation connected to the pulserelays output so that the button turns green when relay is on etc.

In switch function this would have been more simple.

ixo65

The problem is that the VM memory of the LOGO! is not remanent. This means that when you switch on the LOGO! all bits in VM memory are 0.

I would solve the problem differently if I were you. In such a case, I would use a button instead of the switch and connect the button signal to the trigger input of a pulse relay. With the pulse relay you can switch on the retentivity. The pulse relay thus retains its status even in the event of a power failure.

Did you look at my example?

So I did it.

Network input ---> pulse relay ---> network output back KTP700.

 I didn't yet. 

But now that I watched it, yeah. That's what I had in mind too.👍

Thanks again for the help.

ixo65

Did you look at my example?

So I did it.

Network input ---> pulse relay ---> network output back KTP700.