[Mike@Torchmate]

What is the exact sequence of events during this operation.

Does it rapid travel to the cut,and along the way it will come down and sense the material and try to pierce? What happens when it gets to the cut? Does it stop the torch, move it to the home position at the top? Does it come down and sense the material again and cut out the shape? At the end of the cut does the Torch retract to it's home?

This is why a phone call is the best way to trouble shoot this type of a problem, due to the fact that there is a lot of different possibilities depending on the answers to these questions.

Due to the specific question of it is coming down and sensing the material during the rapid travel, I can come up with a few conclusions, and I will list them below.

A) The software is activating the output line during a rapid travel feature, most likely a software setting if it is 100% consistent, every rapid travel movement. Since you say it does it when it is just sitting there not running code, I would say that it is not the problem.

B) The plasma interface relay box itself is activating the height control, regardless of signal from the signal generator, test by turning the signal generator off or unplugging the output connector and see if it still randomly fires while sitting idle. If it no longer does, the output lines in the signal generator may be defective and outputting voltage when it is not supposed to be. To test that theory we would test with a multimeter the output line for +5v DC. If the signal generator was outputting this 5v randomly without being activated by the software, the problem I would say is the signal generator.

C) The relay itself is activating and telling the height control to activate regardless of input from the signal generator. Test by hooking a continuity tester or the ohm setting on your multimeter, to the back of the relay box to the two small screws. Unplug the relay box from the signal generator, and unplug the wires going to the start input on the height control. If it randomly activates the relay (should have a loud audible clicking noise) with no input, and no connection other then power, it would be a defective interface box)

D) If with the plasma interface box disconnected from the start input, you have the AVHC unit powered on and it randomly activates, goes down and sense the material, and fires the torch, then the problem would be with the AVHC box itself.

The key factor to all of these conclusions is that the AVHC unit is receiving the fire signal (closed loop) from the system with no input from the software. It could simply be a loose wire hanging in the wind, and that the software is activating the output line in between cuts. You think since it is a firing issue they must be related, where perhaps it is not. Let me know what other questions you need answered