How would you design a real time application for cnc control in c / c++ ???

@Grotius
Is there a trigger in lcnc that can be used as an event . Like position of any joint changed or something like that.
Or how can that be done.
I don't want to loop the status, just trigger an event. ??

@ Grotius
Could you supply a very basic example of a component and how to compile it without halcompile. KIS.
Most interesting how to compile.
udoS

Hi Udo,

Could you supply a very basic example of a component and how to compile it without halcompile. KIS.
Most interesting how to compile.

The best example for this :
github.com/grotius-cnc/hal-core/tree/mai.../hal/components/test
Where the "make" (script) file shows the gcc compile steps.

Is there a trigger in lcnc that can be used as an event . Like position of any joint changed or something like that.
Or how can that be done.
I don't want to loop the status, just trigger an event. ??

I think events are used by programs like qt. A event triggers something without the need of a endless loop or thread.
In the background qt has it's own thread. I suspect at low level, the event is triggered by that qt thread, but i don't know for sure.

If a status channel would have a qt OBJECT in the header (or at least is qt object compatible), i think it's possible to create a event in the way signals and slots
are used, but i don't know this for sure.

I suggest the status server has is own thread, so polling the status channel at a fixed time or flag makes sense.
I don't have a good advice what will be the best solution in this case. Speaking for myself, i would just poll the status channel.


 

Hi,

> I suggest the status server has is own thread, so polling the status channel at a fixed time or flag makes sense.
> I don't have a good advice what will be the best solution in this case. Speaking for myself, i would just poll the status channel.

if you look at my FalconView project you'll see, that the whole application is event based. Including all values from linuxcnc status. But ...
... there's no trigger from linuxcnc that fires signals or the like.
You have to do it on your own, which in the end means, that you have to poll status channel.

In my case - I use ValueModels to convert polling into signals/events. Statuschannel is read at fix interval and Status reader writes all values into appropriate ValueModels - on every timer call.
Its the ValueModel, that compares the values from StatusReader against the value it holds and when the value changes, than it fires an event/signal.
Thus the whole application can rely on events and status polling is isolated to a single source


 

Thank's to the both of you.
That's what I'm doing right now. Timer and then signals and slots. Then model to view.
@Reinhard: I'm going to have a closer look at your project. Again .
@Grotius: I'lll give it a try and see where I end up.

Thank' again.

Hi Grotius
I'm back and want to continue development with my real time application.
In a global sense, I want to make a "conveyor tracking" function like Beckhoff (Twincat) or Codesys did for example.
Now I settled on the fact that I managed to control the 3d model to hal variables using the scrollbar and textbox
I want to control this model without G-code and scrollbar. Only code in application like function Pick-and-Place (Twincat).
For starting Can you give simple example to do motion for 3 point (for example)?

eoffset component can not work for you? as conveyor traking is perfect ..... or maybe we can insert some sort of distance-limit-disable for prevent traking in to non desired position ....

but some big have special kins for that pourpose .... not om...om .... for example ....

bkt

Ok. This is very similar to what I need.
Do you have any example how to write hal-file with this this component.
In fact, I need to create such a configuration as in this video

- Velocity of conveyor need to set const or counter of external encoder.
- Lim of "sync zone" will be a circle equation or a simple line.
- How I control robot? Use g-code or any else (like pick-and-place).
- How I can switch coordinate systems.
For example : g53 - this starting coordinate system
g54 - This coordinate system of conveyor (which changes over time)

I looked at the examples in external_offsets, but I don’t understand yet which one is more suitable

I try default example of "eoffset" and get some offset. Then I create my configuration and get nothing

 

Hi Roslyak,

Nice you are back.

> For starting Can you give simple example to do motion for 3 point (for example)?
github.com/grotius-cnc/skynet_robot_control_rtos_ethercat
github.com/grotius-cnc/hal-core

In the meantime i coded some components for hal-core.
Like this example : github.com/grotius-cnc/hal-core/tree/mai.../hal/components/test
There are some motion components inside hal-core : github.com/grotius-cnc/hal-core/tree/mai.../hal/components/dofs

In general you can use Lcnc or Hal-core. Hal-core is more hard coded c & c++ and uses a Opencascade 3d graphics displayer.

It looks you got a lot of coding to do. A medium size project.

I am busy with coding some stuff i like to do. 
Once in a while i can help you with specific things if you get stuck.

My advise so far would be, get the kinematic model working in opencascade as your picture show's.
Then use a component like "dofs" to control motor operations in hal. Try to get this running first.
I think you have to send motion commands in xyz positions instead of joint values.
Don't worry about Gcode, offset's or moving conveyors. This is no issue to integrate later on.

And maybe keep it closed source for now.