In this Tutorial – How to connect and setup torch height controller (THC) for plasma cutters using Proma Compact THC 150 and Proma Compact THC SD 

All cables should be shielded. Everything should be properly grounded and earthed. Plasma torch is a big source of EMI, so consider a proper filtering.


There are two common versions of Proma THC controller:

THC controller itself generates “STEP/DIR” signals which drive Z axis accordingly to THC controller measurements:

This wiring scheme itself is sufficient for user to correctly connect PlanetCNC controller and THC controller.

THC controller controls the Z axis via JOG connector of Planet CNC controller accordingly to THC measurements.

-JOG 8 is the input for controlling Z axis in negative direction (connected to DWN output terminal of THC controller)

-JOG 7 represents the input for controlling Z axis in positive direction (connected to UP output terminal of THC controller)

Note: Mk2 and Mk2/4 controllers have different JOG pinout.

Software settings:

In CNC USB controller software you set THC settings in “File/Settings/Axes/Options”.

‘THC enable’:
Enables THC control.

Select axis that will be controlled accordingly to THC controller measurements.

‘Speed only’:
THC control is applied only when machine reaches its max. set speed (THC is not applied when machine accelerates and decelerates).

Gear ratio for speed (to lower speed of axis compensation, softens the sudden moves).

Related CNC Plasma Parts