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General Mach Discussion / Re: Another THC problem
« on: November 13, 2020, 05:00:38 AM »
FYI to all.
I have created a temporary workaround. I have run the step/dir pins from between the mach3 breakout board and the stepper driver through a DPDT solid state relay. I have connected the relay signal to the arc ok output and have also left the arc ok signal connected to the mach3 input pin to utilise the feed hold function if arc is extinguished. Then I have connected the torch up and down outputs from the THC unit to an Arduino board and have programmed it to output a square wave and direction to control the Z axis. These outputs are connected to the N/O side of the relay and the mach3 output through the N/C side. The common is connected to the stepper driver.
Keep in mind that I am only just starting to test this but so far it looks ok. The theory is that when no arc, the Z axis stepper driver is connected to the mach3 board and mach can move Z axis as it wishes. When the arc ok signal is active, the SS relay disconnects the mach3 signal and connects the Arduino board and the Arduino converts the up down signals from the THC to step direction outputs that are now connected to the Z axis. The Z axis stepper can now move up/down according to the THC unit and mach3 has no THC functionality needed. Once arc off, the SS relay swaps control back to Mach3 and Mach continues on as normal.
As I have stated, this is a relatively untested TEMPORARY workaround and I will be getting a THC capable board as this does not allow the use of limits etc but my plasma table is too big of a toy to have sitting idle and I am impatient!
I have created a temporary workaround. I have run the step/dir pins from between the mach3 breakout board and the stepper driver through a DPDT solid state relay. I have connected the relay signal to the arc ok output and have also left the arc ok signal connected to the mach3 input pin to utilise the feed hold function if arc is extinguished. Then I have connected the torch up and down outputs from the THC unit to an Arduino board and have programmed it to output a square wave and direction to control the Z axis. These outputs are connected to the N/O side of the relay and the mach3 output through the N/C side. The common is connected to the stepper driver.
Keep in mind that I am only just starting to test this but so far it looks ok. The theory is that when no arc, the Z axis stepper driver is connected to the mach3 board and mach can move Z axis as it wishes. When the arc ok signal is active, the SS relay disconnects the mach3 signal and connects the Arduino board and the Arduino converts the up down signals from the THC to step direction outputs that are now connected to the Z axis. The Z axis stepper can now move up/down according to the THC unit and mach3 has no THC functionality needed. Once arc off, the SS relay swaps control back to Mach3 and Mach continues on as normal.
As I have stated, this is a relatively untested TEMPORARY workaround and I will be getting a THC capable board as this does not allow the use of limits etc but my plasma table is too big of a toy to have sitting idle and I am impatient!