Siemens Logo Problem

Join Date
May 2010
Location
Finland
Posts
3
Hello everyone! I´m very green new with PLC and i searched for some help concerning my problem with Logo and did find this nice looking site.
Did download today a demo version of Siemens LogoSoft 6.1 programming tool. Did play around a little with the demo software and made a diagram for sequence on and off switching. Seems to me it works ok in the program (I don´t have any actual hardware to try it out)

It hit me what the Logo would do if supply voltage is lost, if the outputs would go all crazy if powered of and back on. What it would need to do in such a case is to stay in the last state as it was when Logo was up and running. this both at black out and when powering back on.

Could anyone explain me how this can be reached and if it´s possible to configure an output in such a way that it would change state if the unit would shut down? An alarm from a auxilary switch on protecting MCB would be one way. But if the fuse wouldn´t trip and the Plc would be at fault, there wouldn´t be any immediate alarm.

Hope that someone could help me out with this one
 
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Anyone who could advice me how to solve this output problem? This is my first try with PLC so i´m a bit confused with this problem. I can submit the logo file, if someone could give some comments.
 
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Logo have a retentivity feature which retains the last state it was before a black out. You have to enable retentivity in the block property for each block. There is also a startup flag M8, which is enabled for one scan during the power up.

You can use both these features to get the result that you want. If you need more help then upload your program and will be glad to help...
 
Thank You very much for Your support! I found retentivity in blocks and ticked that option for all blocks with retentivity. Did not find the start up flag You did refer.

I do not know if pressing the F3 key and going to simulation mode corresponds to powering up LOGO. As now the pulse disconnect/open outputs will pulse when starting simulation.
 

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