hot wire cutting

Hello,

The forum I often browsed and for most problems I found help. Now, unfortunately, the issue has outgrown me. I have a plotter for cutting styrofoam with hot wire.
I need a wire break control in it. The wire is controlled by PWM. The problem is that I would like the control to take place only in a specific case, i.e. when the machine executes a program with (M3) on, the wire breakage would cause the machine to pause or e-stop. My control system works only when current flows through the wire then there is a high state on the sensor output. Can anyone help me solve this problem?

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At the moment the sensor is not connected in any way because it did not work for me under e-stop, I had to have at least a minimum current in the wire at all times, even when stationary.
The high signal from the sensor activates the relay so I can give any signal.
The machine is supposed to stop, because often when it breaks the wire sticks to the material and pulls it.
 Apart from the movement of the wire frames, the machine does not make any other movements.
I wanted to associate this control with the M3 code because my G-code generator allows quick passes past the material without heating the wire.

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Some pictures of your machine would help. tommylight and I have both built hot wire foam machines.
Personally I would use ladder logic for the pause control. I am confused however as
to why your wire breaks often enough that you need a system to pause the program when it happens.
Some questions.-
What type of wire are you using Titanium? NiChrome?
How much tension is the wire kept under?
What gauge is the wire?
How hot are you running the wire?
What voltage is the wire powered with?
What frequency is your PWM signal?

I converted the controller of an old plotter that was burned out. By trial and error method we managed to get it working.
 I use 0.3mm kanthal wire.The length of the wire is 1.5 meters.
 It does not break very often but it is almost always the least appropriate moment when cutting large files.  And my works can be cut even 1,5 h. I use styrofoam for initial molds for plaster decorations.  (Maybe a little from exaggerated economy I use it too long).
I don't know the tension force of the wire and it will be difficult for me to measure it.
I don't know the temperature of the wire either, but I know that with the hardest materials in the dark it doesn't glow. At least that's the setting I use.
The wire is powered by 90V.
I have the PWM set to 100Hz.
Whether the control is needed I don't know now I work without it, but in the old machine it was and sometimes I saved a large piece of material.
I am also attaching two photos from the manufacturer's website of my own now I don't have until the weekend I will be in the workshop.   

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  I will admit I haven't herd of Kanthal wire before. From what I could find online it is an iron chromium aluminum
wire. I would have concerns with a wire that is heated and flexed repeatedly when it contains aluminum . That
would generally be a recipe for stress cracking. Hence why I like NiChrome wire. I would venture a guess that
the wire on your machine usually breaks at the pulley.  Correct?  At least if it's the same as the picture.