THC plasma configs, with HOW TO.

I think that the new Plasmac config will give you all of the error recovery you could imagine.

This is an old topic, but I'm trying to setup it for my plasma table, the problem is I don't find where can I put the Cut Height in the configuration screen, can somebody help me?

Hello!

-- avoiding to open another thread

Let me recap my current understanding of THC: it has two modes, one that reads the arc voltage trough a THCAD board (outputs frequency translated to voltage) and logic happen within LinuxCNC and another where an external "device" sends up and down commands. Hope this is correct.

My goal is to create a simple and cheap machine driven by a board PC (eg. Raspberry).

Since i already have GPIO pins, this should be easy, however Raspberry does not have a ADC.

My options:

1. Use an external board with embedded ADC and logic (arduino), hook to a voltage divider and send up-down commands - not preferred since i would like to use LinuxCNC logic

2. Use an external ADC and voltage divider and send the value to the raspberry (i2c) - can LinuxCNC be configured to interpret the value received over i2c?

3. Use a THCAD board and read the frequency over a GPIO pin. Would the resolution be limited by the RPI?

4. Use Arduino that reads voltage and outputs a frequency so that the LinuxCNC can apply its internal logic - simulate a THCAD basically. Would this even work?

Are those options viable? What is your advice?

Thanks,
Alex

There is not really anything simple or cheap about plasma. the Pi is supported. The Pi V 4 is more or less required for reasonable performance.

1. I would not recommend Too much work.
2. I think there is a bit banging i2c component but its not high performance
3. You could do this if you use the encoder component but throughput will be limited.
4. You do not need a arduino. Mesa says "A functional THC A-D could be made for $2.00 with a 555 Timer VCO and an optoisolater."

5. Use a Mesa 7C81 to utilise the Pi GPIO store.mesanet.com/index.php?route=produc...oduct&product_id=338
6. Consider using a 7i96 and a thcad with your pi. This might cost a bit more but means you are not tied to the pi so can upgrade to a pc if you want later.

tommylight wrote:

TI makes some 3$ chips that do voltage to frequency conversion, they can do 10KHz, 8pin DIP package, forgot the model number, i still have 3 of them collecting dust.

That chip is i think lm331.
There are premade modules on ebay and aliexpress. Try searching "Voltage to frequency converter". 0-10V to 0-10khz.

Use Arduino that reads voltage and outputs a frequency so that the LinuxCNC can apply its internal logic - simulate a THCAD basically. Would this even work?

I am going to try this this week. Will report about functionality with parallel port BOB.