THC control

Hi Roberto,

You do not need the mesa board, I use a parallel port. However, I do not read the voltage. I think the easiest thing for you to do is probably develop some hardware that will read the voltage and then decide whether to move up or down and send a signal to the computer on what to do, (since that is your strong point). That is basically what I do. I bought a THC controller from Campbell Designs and then connected that to the parallel port. I then modified the THC component per the suggestion by andypugh. I am by no means a great programmer, but it was fairly simple and it works fine for me. I can post it later if you like - I do not have it at this computer. One thing I am learning about EMC is you can basically do anything you want.

Any V-F converter would work, though the parallel port would limit your control loop bandwidth vs voltage resolution tradeoff somewhat. For example say that you can read the parallel port at 20 KHz so you can reliably sample an input square wave up 10 KHz. A t a 1 KHz servo thread you would only get ~10 counts full scale ( about 3 bits resolution) so you would have to low pass filter the velocity signal get a usable feedback signal (more voltage resolution), and this low pass filter will limit your Z Torch height axis control loop bandwidth.

Hello brianm,
Thanks for your answer . I was looking ( a lot ! ) in the web how to modify the thc component .
Basically I understand that may be changed and recompiled for suit the needs , but when I was trying to find more info i did not find nothing for a beginner .
Reading your reply and the reply from PCW ( many thanks too ) I come with a different appproach .
Would be relatively easy use the component input and "read analog values" like usb joisticks but I do not know the resolution and speed of this converters.
Also using Arduino to make the A/D conversion and why not something else like torch on, comparations etc...
There are also inxpensives USB SOUND CARDS that usually dont have ac coupling letting use them for dc A/D conversion ( but I dont know if HAL can use them.

At the end I think I will follow your idea !

Just will make a small external comparator and drive the voltage comparation from a parallel port pin (PWM) to set the voltage from Axis UI.
I will try also an experimental way to have the ARK_OK signal from the torch volt ( when working with a good ark I never saw voltages less than 80 v and more than 150 v )
Another experimental idea is to read the ARC_OK - UP - DOWN signals with just two pins ( when UP and Down signals are active will mean ARC_NO_OK ).

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 .
If everithing goes well I will be proud to post the hardware schematics and send some prototypes

Best regards
Roberto

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

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