What is Plasmac?

Hi Guys,

I have been testing out the Sims of Gmoccapy and Axis and what I have come to realise is I do not like how they are set up.

My question is what exactly is Plasmac? I know it is a component that Phill has created, What makes it different to other plasma linuxcnc setups what were made before it?

What I would like to do is get my head around how the system works then I will hire a developer to design a new user interface base on QT.

I plan to in the future sell complete plasma cutting tables so I need a user friendly interface to include with my tables.

In my head, plasmac is 3 components:

1. Patched version of LinuxCNC to include reverse Run
2. Plasmac.comp - a real time THC component
3. The GUI, the remapping and python extensions Phill has built that has become bigger than Ben Hur.

What Sets Plasmac apart from things that have gone before is no gcode probing routines, PID based torch height control and use of external offsets so it only needs X-Y gcode. Plus the GUI sophistication and included cutting rules. Phill has basically rolled up all of the stuff others have done over the last couple of years into one cohesive unit.

I would keep to the script and only modify the GUI as in time I expect plasmac will end up in the core code so it will be much easier to maintain the system for you. I would look at working with these guys to build a plasma specific screen forum.linuxcnc.org/41-guis/34996-another...ect-underway?start=0

rodw wrote:

In my head, plasmac is 3 components:

1. Patched version of LinuxCNC to include reverse Run
2. Plasmac.comp - a real time THC component
3. The GUI, the remapping and python extensions Phill has built that has become bigger than Ben Hur.

What Sets Plasmac apart from things that have gone before is no gcode probing routines, PID based torch height control and use of external offsets so it only needs X-Y gcode. Plus the GUI sophistication and included cutting rules. Phill has basically rolled up all of the stuff others have done over the last couple of years into one cohesive unit.

I would keep to the script and only modify the GUI as in time I expect plasmac will end up in the core code so it will be much easier to maintain the system for you. I would look at working with these guys to build a plasma specific screen forum.linuxcnc.org/41-guis/34996-another...ect-underway?start=0

Thanks Rod,

I will read through that thread tonight.

This might be a very basic question but how does linuxcnc work with components? I take it that there is a core code and the components add on to it.

I would gather that the GUI is just a front end that interacts with the core code and components?

When you loadrt a component, you are loading an object file in to memory
When you addf a component, you are adding that to a particular thread, Usually the servo_thread
Lets just talk about the servo_thread for a moment.

LinuxCNC calls this thread 1000 times per second. Each component that has been loadrt'ed is called in turn so components need to be short sharp and sweet so that everything gets done before the next call. If it doesn't then latency is exceeded an an error is reported.

Components are written in a variant of C and are compiled and installed with halcompile. hlacompile wraps the necessary complex C headers around the source code and compiles to object code (executable code, like a DLL in windows). Optionally halcompile will install it which just copies it to the correct folder in LinuxCNC so it can be found.

eg.

will compile and install my_comp.comp

If you are not using run in place, you need to use sudo so you give halcompile the rights to work in system directories.
This is Linuxcnc's best kept secret as you can add stuff to the environment yourself and it acts as if its part of the base config.
See
linuxcnc.org/docs/devel/html/hal/comp.html

Most hal components are very short and sharp. Plasmac is huge by comparison. The other option is to create multiple components that are joined together to do the same job piece by piece. I favour this approach as it compartmentalises each function from errors in other sections of the code. This is also more consistent with the LinuxCNC paradigm. But it does come at the cost of more complexity in Hal.

The other option suggested by Andy is to rewrite the task and io modules which are also loaded in the ini file to be plasma specific. This is something I'd like to explore if I had the time.

Here is a very cool/functional gui that @BigJohnT is working on: forum.linuxcnc.org/41-guis/36506-qtpyvcp-plasma-gui

Phill

Cut two sheets today with your latest release. Total success, 100% yield. Reverse run saved two parts that errored out because of tip ups that cause torch break away errors. Had an error while in IHS skip distance, it appeared to recover OK. The plasmac probing is so fast I may have missed it, busy look at the big picture to notice the ohmic led.

John