Plasma Questions

rodw

Ok, here is how I have used the GUI values on my machine.

The Z axis speed is usually reduces from its maximum capability to keep the torch from over shooting on corrections. I know this is not the best but it is the way most lowcost systems cope with not needing to change the THC gain for each set of cutting conditions. So on my system I just multiply the Z max velocity from the .ini file by the GUI percentage and set the z axis pid max-output parameter to it when the THC is active. This really is working as a limiter to the velocity command to the 7i76e step generator.

Two of the GUI items relate to piercing and will be used in your part files or in O code subroutines. I use O code subroutines for probing and piercing. The pierce height (gap) is the height of the torch above the top surface of the work piece and is usually the last move of your probing sequence. The pierce delay is the time period between your control receiving the arcok or ok to move signal from your plasma power supply and the movement of the torch to the cutting height (gap).

The Corner lock is on of the keys to good cutting, it is also called Velocity Anti-Dive by some. The value from the GUI is the amount of reduction from the requested velocity. If the current speed is below this set point the movement of the z axis is frozen until it is equal or greater. Connect the GUI pin to the thc.velocity-tol pin. The corner hold function is always on in the current THC component. You can trick the enable check box into actually doing something by having it force the threshold value to 100 when disabled.

The G0 gap is also known as the safe Z height. I am actually not using this right now because this is set by my PP in the G code part files.

The correction pin in the GUI is connected to the thc.offset-value pin.

I haven't done the limits yet. The Z up and down LEDs are from the up/down inputs from an external thc. I haven't set up the calculated values yet to drive the leds from the THC component.

I'll post my configuration files in a few days after I clean them up some. Lots of messy stuff from experimenting to get things to work together. Starting lcnc from the terminal and halshow are your friends.

John

John, thanks for your detailed reply. It was very helpful and it helped me to connect a few more pins. I think I've got all the THC pins connected but wanted to check them all off to check.

I think I can see a way to simply generate the up and down LED's. The Mesa stepgen velocity pins change sign based on the direction of travel. In my setup, down is negative and up is positive.

The HAL abs command has a pin for the sign. 1 = negative, 0 = positive. One signal will need to be inverted. I'll have a go at it in the morning and if I have a win, I will post the code.

I understand the heights and delays feed into the touchoff o procedure but do we need to connect them to something or is that already done in the config files? I saw that there were some digital pins that connect hal to gcode so wondered if there was something similar we needed to do. (be gentle, a couple of weeks ago, I knew nothing about gcode and I've only learnt about 4 of them so far.)

rodw

None of the pins from the GUI are connected for you! When I made the decision to go with the plasma version of Gmoccapy I thought things would go fast and easy because all the stuff that requires detailed operation knowledge of the control was done for you, wrong, it has been a tough steep road but I am getting to the end. Now I am thinking of scraping this and starting over doing things much cleaner instead of fixing each case and moving to the next one. While most everything you need to know is in the docs finding it and understanding it when you don't really know where you are going is not always easy.

There are several ways to connect the pin values into you operation. They all go through the hal one way or another. I am using O codes (sub routines) to do probing and piercing right now. Keeping the probing and piercing motions out of the main line G code part file makes them easier for me to understand and trouble shoot. Also it helps to keep the part file smaller, many of my part files are between 12,000 and 15,000 lines long for a sheet of parts. Look in the documentation here:

linuxcnc.org/docs/devel/html/remap/remap...i_file_configuration

And in the next two sections for what you need to know to read .ini and hal file values in to G code files. Why this information is in this location escapes me but it is covered. I read both .ini and hal values into my files. Of course you don't have to do any of this if you just control everything with your PP. I actually could do that because I only use two different sets of torch consumables, they run at the same cut height but pierce differently.

One thing I still have not figured out is how to read values from the .ini file into hal files other than the main one. I ended up having to make pins in the main hal file (actually install components) and then use them in the later hal files (the ones to connect your GUI tabs to the world).

John

Thanks, John I knew it wouldn't be as easy as it looked! gmoccappy seduces you withits cool interface and then you really have to work hard!

There is a caution in that link that says

this section doesn’t really belong here but since it comes with the same branch, here it rests for now until its clear this will be merged. It should go into the gcode/overview Named Parameters section.

So now you know why!

I sorted the Z up and Z down signals with The LEDs now turn on whenever the axis is moving.

I hooked signals from the Z axis limit switches on the plasma tab to But the screen LEDs don't change state despite being able to see the state change on the pin in halshow so I don't know whats going on there. Is that the intended purpose or it it meant to be THC related? It does not seem to be a particularly useful feature the way I've done it when linuxcnc raises an estop window anyway.

I think the torch breakaway switch need to come out on the GUI somewhere. Whilst mine generates an estop, it would be nice to know why it stopped from the console.

I still don't understand what plasma.hal-lbl-corr is meant to display.

I think I've had enough for today's session!

rodw wrote: T
I still don't understand what plasma.hal-lbl-corr is meant to display.
/quote]

Now I do! - From your earlier post thanks!

The correction pin in the GUI is connected to the thc.offset-value pin.

rodw

The GUI screen is really just a collection of possibilities. What you is similar to what I was thinking about doing with the up/down leds. I actually think they are there for people that have a Proma type external THC so you can see when the THC is commanding the the torch up and down. The z limit leds in the plasma tab where most likely met to interface with some soft limits for torch movement. Some of the Mach3 screens for THCs have limits you can set for when the THC is working. Under Mach you loose the real soft limits when using an external THC.

The torch crash switch is displayed on an led on my GUI and is connected to the estop logic.

John