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Maybe a first step to try would be just a simple P loop where you replace
the constant "correction_vel" with the actual voltage error (scaled by PGain)
so the correction is Proportional to the error.

that is, replace this:

if(torch_on && arc_ok && vel_status){ // allow correction
if((volts + voltage_tol) > volts_requested){
offset -= correction_vel;
}
if((volts - voltage_tol) < volts_requested){
offset += correction_vel;
}

with this:

if(torch_on && arc_ok && vel_status){ // allow correction
if abs(volts_requested - volts) > voltage_tol {
offset += (volts_requested - volts)*PGain;
}
}

Hi Guys,

A long time ago I cobbled up a THC component to use with my Mesa THC-AD card. It works for the most part, but I know it can work much better if I can incorporate PID into it. I'm kinda stuck and need some help or a push to get this to work with PID. I think it would be simpler from a user stand point to have the PID a part of the component instead of having to use an external PID...



Thanks
John

I'm guessing any sections in the hal files clearly marked THC would be a good place to start...

John

Thanks for the reply guys.

I guess my main trouble is configuring what I have working into a plasma system. I have looked at your code John and am just not sure where to start modifying and what I need to leave behind as far as the THC goes. I understand that the stepper vs servo as far as EMC2 is concerned shouldn't really matter. But like I mentioned what should I change/add to the config I already have. This is a slightly modified version of the m5i20 config that was in ver 2.2.1 I believe which I have running a 3 axis system. I attached the files below.

If you can point me in the right direction I would appreciate it.

Thanks

This is my stepper config using THCAD but like Andy said the only difference is the servos vs steppers part.

gnipsel.com/shop/plasma/plasma.xhtml

John

tzak wrote:

I wanted to get a thread started on setting up a 3 axis plasma with THC using the Mesa 5i20 card. I know that there is some documentation with regards to stepper configs however I wanted to see if anyone has had any success using servos

Conceptually, and as far as EMC2 is concerned there is no difference. This sort of thing is handled by the "A" in "HAL" (Hardware Abstraction Layer).
Basically any signal that goes to a stepgen in a stepper config just gets sent to a PID in a servo config.

I wanted to get a thread started on setting up a 3 axis plasma with THC using the Mesa 5i20 card. I know that there is some documentation with regards to stepper configs however I wanted to see if anyone has had any success using servos and the THCAD from mesa. I have a 3 axis router using servos and the Mesa card, however I wanted to know how I can modify what I have to included THC and what other hardware I will need.

thanks

I wrote an up/down THC comp based on my THC comp. I'll have to find it... ah here it is.

gnipsel.com/shop/plasma/plasma.xhtml

You will have to follow the short instructions to install the comp from here:

linuxcnc.org/docview/html/hal_comp.html#r1_11

John

i am not familiar with that device , but if you have a link to the manual or diagram , we can assist further
if they are just signals , connecting into EMC should not be a difficult task , as their are a few plasma users with torch height controls
of various types working fine

their are configurations for Torch height controller within emc , see the examples for THC300
and also this post may help
www.linuxcnc.org/index.php/english/compo...mit=6&start=12#15198

are you connecting via a second parrell port ? , or other card

Hello guys
I'm new to EMC2 and Linux so i ask you kindly be very gentle.

I purchased from Agelkom Capacitive THC
The device is sending to pc four signals:

Torch UP
Torch Down
Torch in position (ARCOK)
Probe (Touch Plate)

As long it concern me, iti is a very useful device because it doesn't need to touch never sheet metal.

Can anyone can help me to integrate this device in EMC2?
Thank you in advance

Hi all

I was writing a new comp for thc boxes.

FIRST OF ALL I AM NOT A PROGRAMMER
So ,please, apologize if the program has a bad style

I believe is now ready for testings ( I am using it since two mounts and look fine ...)

BUT STILL EXPERIMENTAL (off course:-)

Hoping someone will find it useful

Hello all ,
Studying C language I was writing a .comp for interface a virtual jog wheel .
It has accelerated response , if the mouse wheel is turned slowly the out will be step by step.
but if you spin fast the mouse wheel it will be cubic steps .
I found useful for my plasma table ( just X Y ) but i think it may be useful for more axis too
If someone is interested ...

Best regards

Thanks a lot ! Looking for a lot but never find it !

My first impression is that, really, there are not limits on what can be done with EMC2.

I will begin to study just now .

Best regards

hominux wrote:

Now the big problem for me !
I NEED/WANT to learn how modify the thc component to do that.
Any help wil be greatly apreciated .

This page explains how comp works, and how to recompile and install:
linuxcnc.org/docs/html/hal_comp.html

Basically make the changes you want to thc.comp then type comp --install thc.comp