Hi,
This is my first cnc machine so I was not aware the controller itself would need to support that.
THC is a realtime function, that is to say that it must respond instantly, or within a few microseconds of a THC_UP or THC_DOWN
signal. This means that the hardware must enact it. If the signal were propagated back to Mach and Machs response propagated
back though the controller the communication delays are too long.
You need to do some research but I'm guessing that your controller does not support THC, many of the Chinese made controllers
do not.
Most of the US and European made controllers do support THC.
reuelt is wrong, the Ethernet SmoothStepper DOES support THC in Mach3, and has done for some years. The USB SmoothStepper
by the same company does not support THC, the USB communications are deemed being too subject to EMI to be useful
for a plasma table. He is confusing THC support in Mach4.....it is being Beta tested now.
I tried setting torch up/down signals to z jogging input but it wont move while running g code.
That is correct, once the Gcode interpreter has control of the motion controller then you can't jog at the same time.
If you like, that is the challenge of THC support.
Your choices are:
1) Forgo THC altogether
2) Use Machs parallel port (Windows 7 32 bit or earlier required)
3) Buy an external motion controller like a SmoothStepper that does support THC
4) Use Mach4??
I have suggested Mach4 because they have released ( as development version only just yet) a script based THC solution.
At the start of this post I commented that THC is a realtime function, and the communication delays preclude a software
solution. Mach4's communication delay are much less than Mach3 and so NFS have written a script (software) solution.
Provided the movement required is not too rapid then it will work. If your machine cuts very quickly and demands
rapid THC movements then genuine realtime THC support is required.
Craig