Advanced Search

Hello gentlemen.All my attempts to use voltage tolerance in THC comp have failed. When I try to uncomment the line 'net thc-volts-tol pyvcp.volts-tolerance thc.volts-tol' in my postgui.hal I have an error: pin thc.volts-tol doesn't exist. Indeed, I can't see this pin in a Hal meter. Although my project is located in only early phase I plan to use voltage tolerance to avoid Z jitter. (Maybe I'm wrong). I would like to ask you how can I put on the volts-tolerance function if it's possible at all. My hardware are THCAD and 5i20, soft LinuxCNC 2.5.0 and config files are below. I will be really greatful for your help.
Andrew

Looking at the thc man page I don't see the pin or parameter spelled that way. I do see a parameter thc.voltage-tol float rw The deviation of Tip Voltage before correction takes place. Start your config and open up Show HAL Configuration. Look at the thc pins and thc parameters for correct spelling. I like to highlight the pin/parameter then press the middle mouse button to copy (it's the only way that works) then using the middle mouse button paste the pin/parameter name into my hal file. Also remember that any pyvcp pin must be in the postgui file as named in the [HAL] POSTGUI_HALFILE. See the hal section of the ini in the manual for more info.

I think I finally recovered from my vacation... I hope.

JT

John, thank you for your reply and help. I took the basis for these configuration files : git.linuxcnc.org/gitweb?p=linuxcnc.git;a...53913b1d5fce9905776a
and I think there are not any mistakes in it.
Regards. Andrew

Thanks for pointing me to the typo in the sample config. I see that line is commented out for some reason. I'll fix the sample config.

Edit: I think it is commented out because you can't set a parameter like you can a pin. I'll have to see...

JT

is there a way to modify THC300 configuration to work with one paralel port?

bdrotaru wrote:

is there a way to modify THC300 configuration to work with one paralel port?

I have no clue, the THC300 configuration is so complicated that only one person in the world AFAIK has made it work and that was the author. It really should not be part of LinuxCNC anymore... IMHO.

JT

It really should not be part of LinuxCNC anymore... IMHO.

I do agree!
Also some other stuff should go away ore be placed in the correct position.
There are several sim configs in the config folder, insteadt of being in config/sim

Tahnks for the files!

Norbert

Your welcome

JT

Hello Everyone,

We made a plasma cutting machine and now change the controll software to LinuxCNC.
It works good but I have some problem about THC.

I use Mesa 5i20 with Mesa THCAD 10V.
The plasma source is a Hypertherm Pmax 1650.

For the thc control I add the following parameters:
vel-tolerance: 5
volt-setting: 82 (from the user manual, finecut 40A, 3mm thickness steel, we measure it during cutting and it is good value)
volt-tolerance: 1

If I enable the THC the head is move only down and crashed into the plate.
I changed the presage of the thc.vel-scale to negative to look what happen and the head is rise up more than 100 mm from the plate.

I look in the show hall config - thc.zpos.in and it is very high value.

If I had disabled the THC the head was moved down. And after manuall moving the Z it is also make a correction move.

Have You got any idea what is wrong?

Thank You!

Regards,
Csaba

I would start by using hal watch to make sure the THC voltage is correct when the torch is working.
That is if the torch is cutting at 82 volts is the THC voltage in Hal also 82 volts?
This will confirm the voltage is read and the scale is correct.

Rick G

Ricks advice is good, check that the voltage is scaled correctly first.

One other thing missing that may or may not be important is that the encoder scale is never set.

It looks like you are assuming that encoder scale defaults to 1 and it may in fact have this default
but I dont see that specified anywhere in the hostmot2 documentation so I would set the encoder
position scale in the hal file.

Does the Hypertherm Pmax 1650 have different torch voltage divider settings, or are you using raw torch voltage and an external voltage divider?
The Mesa THCAD 10V expects a 0-10 volt input.

If all else is well and the voltage is incorrect the offset and scale of the voltage are set here in your plasma-5i20.hal

Rick G

I don't have a lot of time to look at your files right now (work demands) but I can offer up my old 5i20 config files for my plasma torch for comparison.

JT

Thank You for the answers!

I watched the encoder scale in the hal config. It is 1, it seems that the default scale parameter is 1.

The HT plasma source has an own arc voltage output with max 300VDC. We use resistances to reduce it max 10V for the Mesa THCAD 10V.

We have made some test cutting to check the thc.volts.
Material 5mm thick steel plate , 60 A - according to the HT manula the arc voltage is approx 135V.
During cutting I see the halconfig/ pin / THC / thc.volts and the thc.zpos-out.

Test 1: volt setting is 135V, Velocity tolerance 5, Volt tolerance 1
Result: head is crashed into the plate, thc.volts is changed betwen 100-115V, thc.zpos-out is below -30 after a 100mm cutting.

Test 2: volt setting is 100V, Velocity tolerance 5, Volt tolerance 1
Result: head is rised, thc.volts is changed betwen 120-136V,

Test 3: volt setting is 124V, Velocity tolerance 5, Volt tolerance 1
Result: head is crashed into the plate, thc.volts is changed betwen 124-135V, thc.zpos-out is below -30.


One more remark, if I uncheck the Enable THC function after the test 3, the Z is rized up with the value of the thc.zpos-out.



Regards,

Csaba

You probably have the THC scale/offset wrong

Note that if you use a negative THC scale the THC offset must also be negative
(or set the encoder scale to -1 and set thc scale and thc offset to positive numbers)

You can verify that you have the scaling right by monitoring
the thc components thc.volts pin while varying the input voltage.

The next thing is to verify that the correction motion direction is correct for
too high and too low thc voltages relative to the thc.volts-requested pin