XYZA Simulation Install Problems

I've been using CAMotics for some time to visualize and check G-Code programs. I'm now hand coding some simple programs with a fourth axis (XYZA). I've found CAMotics doesn't recognize the rotary axis and also doesn't recognize the global variables used in LinuxCNC, like #<_variable>. So, in a weak moment of delusion, I thought I could install a simulation version of LinuxCNC on my office computer to verify G-Code files. Great idea, I've now spent 2 solid days on it but I'm "almost" there.

I have a VirtualBox on my office computer for Windows/Fusion 360. I've been able to install a simulation mode LinuxCNC 2.9.4 (bookworm) on the Virtual Box. I could not find a four axis (XYZA) simulation version so I've installed this "sim.axis" XYZ version. It simulates fine for 3 axis (XYZ). I'm trying to add a fourth axis to this version. I think this can be done by modifying only the axis.ini file? But, with the mods I've done, the simulation doesn't move in the axis display and then faults with "joint 3 following error".

If anyone has insight in this area I'd sure like to find out what I'm doing wrong. Attached is the axis.ini file with mods noted. If you can offer assistance I'd be grateful. Thank you.

Your core assumption is unfortunately mistaken, it cannot be done by only modifying the INI file, coresim.hal is only 3 axis, the fourth axis will f-error as it is not receiving any feedback, this is expected behavior.
My suggested quick fix, in your INI file after

HALFILE = cooling.hal

add a connection to a local file like

HALFILE = fouth-axis.hal

then create the file next to the ini file with contents

net Apos joint.3.motor-pos-cmd => joint.3.motor-pos-fb

This will allow you to move your fourth axis, don't expect the rotation to look like what you expect I think A axis is rotation around X, so it might look unexpected depending on what your fourth axis does, but it should work.

If you are looking for a deeper sense of accomplishment, read the coresim.hal file and research and understand what it is doing, and why it is needed, that will get you much more satisfaction and future know how.

Thank you. This morning I started to realize the *.hal file(s) would be involved. I implemented your fix and it seems to work, at least for jogging and MDI. Thank you.

I'm still getting an "Unexpected real time delay". Also having some trouble with homing as I don't know the configuration in sim.axis. I could likely strip the homing out and fix the real time delay. However, trying to load a program file locks the simulator, infinite loop which eventually crashing VBox.

Poking at the MDI I found another problem for my use. This model rotates the spindle about X and what I need is to rotate the part around X. In the first case the part is fixed to the table and the tool tilts relative to both, tilting the spindle. In the second case the part rotates relative the the table and the XYZ cutting axes are fixed to the table, rotary table on X axis. I'm surprised as I suspect the rotary table on X is much more common that a tilting spindle (as a 5 axis machine would have).

I could likely dig thru the *.hal files and get a 4th axis working, time if the constraint here. But I doubt I could implement a new motion control model. I have it working on my mill but that was developed with PnCconf. I suppose I'll look for another way to test G-Code files.

Thank you for your help.

I found the "locking up" mentioned above was due to a loop counting in the wrong direction. I'm back to the stock XYZ sim.axis version. Other than the "real time delay" at start up this seems to work.

For hand coding, which is what I wanted the simulator for, I'm only doing fourth axis positioning. If I just comment out the A axis moves I can go a long ways towards de-bugging code. Then uncomment and carefully check the A moves before going to the real machine. Should work OK.

But if anyone has a XYZA simulator that works like a mill with rotary table I'd sure like to get a copy. Thank you.