Is this a typo in the PNCCONF setup for Qtplasmac

See where it says: "Divider Ratio or Series Resistance"

Should it be: "Divider Ratio FOR Series Resistance"

I used 4 x 470 Kohm resistors in series with the THCAD-10 input.
Measured the total resistance of those when connected in series and got 1.886 Megohm.
This gives me a ratio of 19.86

However, PNCCONF does not accept this number, and resets itself to 20.
So I thought I could choose to enter the series resistance value directly and PNCCONF had been programmed to notice the very high figure and realise this is the resistance value and not the ratio. But now Qtplasmac is showing about 800v on screen when I start it up.

That made me think about the possible typo mentioned above.

Keith

"Divider Ratio" is for if you use a plasma cutter with a CPC port and are using the inbuild divider

"Series Resistance" is if you are using full arc votage and a series resistance. Enter the value of the resistance you are adding, it will calculate the ratio.

Ah I see, cheers Phill.

And very sorry for bothering you when I should have just looked in the PNCCONF help file. I'll try not to be so dumb next time.

Well, looks like I've got something else going on then. Initially I entered my series resistance value 1886000, but when starting Qtplasmac the arc volts display is fluttering around 800v.

Before I seen your reply I tried a value of 20 in the Divider Ratio box, yet when starting Qtplasmac again, the volts display is still hovering around the 800v mark.

I measured the output frequency of the THCAD and as expected got 121 Khz which matches the calibration sticker 0v value.

Keith

Can you look for in qtplasmac.prefs in the [PLASMA_PARAMETERS] section there should be values for Arc Voltage Offset and Arc Voltage Scale = 1.0

An easy way of posting your config IF QtPlasmaC starts is on the PARAMETERS tab there is a BACKUP CONFIG button

[strike]Did you set the scale and offset?

linuxcnc.org/docs/devel/html/plasma/qtpl...c.html#qt_mesa-thcad

There’s a calculator there.[/strike]

Also, I’d you click backup on the parameters tab, it makes a nice compressed file for posting here, and includes a couple extra files that help us help you.

Edit: whoops, that’s calculated by pncconf now.. carry on :laugh:

Haha guess Phill beat me to it! :laugh:

Keith, it looks to me like this PnCconf config was saved to an existing directory. Try again with the same .pncconf file but rename the original directory first.

phillc54 wrote: Keith, it looks to me like this PnCconf config was saved to an existing directory. Try again with the same .pncconf file but rename the original directory first.

Phill,

that PNCCONF file was off a USB drive, because I copied all the config files from the actual plasma table PC, so I could view them back on my Windows PC in the house, for learning about them.

OK I'll go and get the files you requested.

Keith

I was a bit unclear...

What I meant was to rename the existing ~/linuxcnc/configs/BEEFYS_PLASMA directory then run PnCconf and open BEEFYS_PLASMA.pncconf with it and run through to the end to create a new BEEFYS_PLASMA config.

Hmmm, I don't see any such BACKUP CONFIG button on the parameters tab. I've attached a photo.

In the meantime, in Qtplasmac.prefs:

Arc Voltage Offset = 0.0
Arc Voltage Scale = 1.0

Keith