Hi,
How would you suggest I connect this?
I have see youtube videos and read people using this THC but no one sharing how they got it to work with Mach 4...
The THC3T-02 unit you have bought is a HARDWARE torch height control unit, it does not 'work with Mach4' at all,
it works totally independently.
Basically you insert the unit between the step and direction outputs of the BoB and the unit adds pulses to those
coming from the BoB (normally) to make the torch go up or down as necessary to maintain a constant arc voltage.
The Hypertherm has two outputs and one input.
One output is a voltage sample of the arc voltage, ie an analogue varying voltage. The THC unit uses this voltage to
decide whether the torch needs to go up or down, so this output would be hooked to the THC3T unit.
The second output is a set of normally open relay contacts inside the Hypertherm. The contacts close when the plasma arc
is established, and is called the ARC OK signal. It really needs to be hooked to both the BoB AND the THC unit.
The BoB/ESS/Mach need the ARC OK signal to know when to start executing X and Y moves, and alternately if the ARC OK signal
goes low, ie the arc has stopped for some reason then Mach knows to stop executing X and Y moves.
The THC unit also needs to know if the ARC OK signal is high, it uses this as a signal to start controlling the Z axis (up or down)
to maintain the arc voltage. In absence of the ARC OK signal the THC unit does not try to drive the torch up or down......why
would you if there is no arc?
The one input into the Hypertherm is to tell the plasma to start an arc. It requires a closure of a set of relay contacts, the
relay will be controlled by Mach/ESS/BoB. Thus when you want to start cutting something Mach signals the ESS which
signals the BoB which energizes the relay which closes it output contacts and starts the plasma.
When the plasma arc has started the Hyperthern signals ARC OK (closes a set of contacts), which signals the BOB/ESS
which in turn signal Mach to start moving X and Y axes. The same ARC OK signal could also be hooked to the THC unit
OR Mach could copy the ARC OK signal from the Hypertherm TO the THC unit. I think the later approach is best but
either would work.
Another issue I noticed is without the THC connected I can jog the Z up and down BUT with the THC connected (wired) Mach will only let me Jog the Z axis up, not down...if i press up it goes up, if i press down it still goes up...any clue as to why?
As I said before the THC3T-02 is a hardware THC controller, it becomes the master of the Z axis. I'm surprised that you can jog the
Z axis at all with Mach, remember the THC3T unit is between the BoB (the bits that Mach can control) and the Z axis driver.
If the THC3T unit decides the Z axis is not to go down then don't blame Mach/ESS/BoB, that's the THC3T making that decision.
I think you are confusing a hardware controller like the one you have and the TMC3 that the ESS is optimized for.
The TMC3 signals the ESS to make the torch go up or down but that information is relayed back to Mach so it knows
that its a little higher (or lower) and has the DRO reflect that. Note that the TMC3 signals the ESS direct so that the up/down
change can happen immediately. You could have the unit signal Mach to go up a bit or down a bit but the communication
delays from Mach through the ESS make the control sluggish. That is the difference between realtime control, ie immediate,
or near immediate control and script (also called software) control which is slower.
Craig