Hello Guest it is April 13, 2021, 01:14:39 PM

Author Topic: Mach 4 THC  (Read 2171 times)

0 Members and 1 Guest are viewing this topic.

Mach 4 THC
« on: May 24, 2018, 02:16:38 AM »
Hi Everyone
I have a proma THC and it works really well under mach3, however I want to use mach4 due to the fact that it is maintained. Also this Windows upgrade issue.
I have the leds showing that the THC is sending the signal through the UC100. The UC100 diag is showing the signal, so why is the Z axis not moving?
Any help would be great.

Many thanks
R
Re: Mach 4 THC
« Reply #1 on: May 24, 2018, 02:45:50 AM »
Hi,
I don't believe the plugin for the UC100 supports THC in Mach4.

The only Mach4 capable controller that I am aware of that has support for realtime THC control is Vital Systems HiCon board. I may well be wrong here, I'm sure
that others will chime in if they know of other THC capable boards.

For THC to be effective it nees to happen very quickly, responding in tens of microseconds and must therefore be done by the hardware controller. Mach4 running
on a Windows PC cannot get close to that sort of response but perhaps tens of milliseconds, about 100-1000 times too slow to be truly effective.

Hardware manufacturers of Mach4 ready boards are where they were about five or so years ago with Mach3, they had some hardware controller features enacted but not all.

CNCDrive, the manufacturer of the UC100 and its sibling UC300 have only had a Mach4 plugin for a year or so. I imagine it would be a big challenge to develop THC support
AND support their existing Mach4 customers in that time frame.

Craig
My wife left with my best friend...
     and I miss him!
Re: Mach 4 THC
« Reply #2 on: May 24, 2018, 09:14:42 AM »
While reaction times for a THC do need to be fast, the issue is not as
severe as you describe. Indeed, since the Z axis is often a stepper motor,
the reaction time is limited by the motor and system mass to something
on the order of a few milliseconds. This is adequate for all but the
fastest THC systems.

The reason that the Up/Down signal feedback approach does not work
in this case is because there must be support in the motion controller
for these signals, and most do not have it. Vital Systems has created
this support in their motion controller and has also created a custom
screen set to configure its operation.

With Mach3 this support was supplied by the parallel port driver. Mach4's
core does not currently provide this support, nor do most external motion
controllers that work with Mach3. Artsoft is experimenting with THC support
within Mach4 but it may still require some updates to motion controller
plugins.

There is an alternate approach, utilized in the Proma "SD" torch height
control interface. It is to pass the Z axis step and direction control
lines through the THC and the THC takes over control of these signals
while the plasma is in height control mode. This operational mode is
not present in the basic model of the Proma THC.
Steve Stallings
www.PMDX.com
For PMDX product support, please use PMDX forum or direct email for quickest response. We do not use this forum as our primary product support site.
Re: Mach 4 THC
« Reply #3 on: May 24, 2018, 06:46:15 PM »
Hi Steve,

Quote
Artsoft is experimenting with THC support
within Mach4 but it may still require some updates to motion controller
plugins.
That sounds interesting, do you have any details?.

I looked at coding a THC routine with Lua and existing Mach scripts but found refresh rates of 10-20 ms
and I thought that too slow to be of use. However as you point out steppers have done a decent job
for many people and they are not likely to have response times of less than 1 ms.

Perhaps refresh rates of 10-20 ms are not as far out of contention as I'd thought.

Craig
My wife left with my best friend...
     and I miss him!
Re: Mach 4 THC
« Reply #4 on: May 24, 2018, 09:03:02 PM »
I had the impression that the Artsoft THC experiments were done using LUA scripts,
but I am not positive. They did tell me that their setup required support for using
an "out of band" motor offset stacked on top of the regular Z and we at PMDX are
not yet set up to handle something like that. Also the experiments were done with
a board that could read an analog input. THC screens had been worked on but have
not appeared in any of the beta releases. I suspect they will hold off releasing anything
until at least one motion control vendor can fully support it.
Steve Stallings
www.PMDX.com
For PMDX product support, please use PMDX forum or direct email for quickest response. We do not use this forum as our primary product support site.
Re: Mach 4 THC
« Reply #5 on: May 24, 2018, 10:26:01 PM »
Hi Steve,
yeah that out-of-band thing is a clever idea. If I'm not mistaken there are already APIs for just
that thing.

Sounds like my thinking was not so far off the beaten track....usually my thinking is not so much left
field... but off the planet!

Craig
My wife left with my best friend...
     and I miss him!

Offline tjb1

*
  •  13 13
    • View Profile
Re: Mach 4 THC
« Reply #6 on: June 14, 2018, 09:58:21 AM »
Am I correct in reading that Mach4 is not able to support Up/Down signals from an external monitor?  I was planning on moving to Mach4 from LinuxCNC due to my lack of Linux knowledge and am working on an Arduino based control that will monitor voltage and send Up/Down signals through the G540/UC100.
My wife left with my best friend...
     and I miss him!
Re: Mach 4 THC
« Reply #8 on: June 15, 2018, 04:03:13 AM »
Hi,

Quote
Am I correct in reading that Mach4 is not able to support Up/Down signals from an external monitor?
Not quite, Mach4 has defined THC signals like THC_UP and THC_DOWN but it doesn't do anything with them. They are meant to be passed to the external controller plugin
and then to the controller board, in your case the UC100. Unfortunately the UC100 cant do anything with them.

CNCDrive, the company that makes the UC100 and its bigger brother the UC300 have only had a Mach4 plugin for about a year. It has not yet seen the development
of features that some of its more mature competition including THC. To give CNCDrive credit though their Mach4 plugin has proven to be remarkably reliable and trouble
free even if it doesn't have many controller only realtime features.

Craig
My wife left with my best friend...
     and I miss him!