linuxcnc/configs/lagun_gmoccapy

Lagun Milling Machine - GMOCCAPY Configuration

LinuxCNC configuration for a Lagun 3-axis (X, Y, Z) milling machine with servo drives, controlled by a Mesa 5i24 FPGA card and the GMOCCAPY GUI. Units are imperial (inches).

Originally generated by PNCconf (July 2024), then modified for GMOCCAPY and dual-encoder feedback.

Files

File	Purpose
lagun_gmoccapy.ini	Main config: axes, PID gains, encoder scales, limits, MDI commands
lagun.hal	Main HAL: loads drivers, wires encoders/PWM/PID/GPIO, tool change
xhc-whb04b-6.hal	Pendant HAL: jog, axis select, feed override, macro buttons
gmoccapy_postgui.hal	Post-GUI HAL: connects tool offset display to GMOCCAPY
shutdown.hal	Shutdown HAL: currently empty (placeholder)
tool.tbl	Tool table with 6 tools (T0-T5)

Hardware

Controller

• Mesa 5i24 PCI FPGA card (hm2_pci)
• 6 encoder channels, 6 PWM generators
• PWM frequency: 15,500 Hz
• Servo period: 1 ms (1,000,000 ns)

Servo Drives and PWM Mapping

Axis	PWM Channel	Output Scale
X	pwmgen.00	+1
Y	pwmgen.02	-1 (inverted)
Z	pwmgen.04	-1 (inverted)

Encoder Mapping

X and Y each have two encoders (motor + linear scale). Z has only a linear scale.

Signal	Encoder Channel	Scale (counts/inch)	Purpose
X linear	encoder.00	5085.5	Position feedback (used for joint FB)
Y linear	encoder.01	5085.4	Position feedback (used for joint FB)
Z linear	encoder.02	-10075	Position feedback (used for joint FB)
X motor	encoder.03	-27939.6	Velocity/damping feedback
Y motor	encoder.04	27453.6	Velocity/damping feedback
Z motor	(none)	N/A	Not installed

GPIO Pin Assignments

Relay outputs (active low / inverted):

GPIO	Function
041	Spindle on/off relay
044	Z-axis servo enable relay
046	X-axis servo enable relay

Button inputs (active low, currently unused/commented out):

GPIO	Function
027	Button (unassigned)
028	Button (unassigned)
029	ESTOP button
030	START button
031	STOP button

The button inputs are configured as inputs but their HAL net connections are commented out because they were causing unexpected machine shutoff.

Dual PID Feedback (X and Y Axes)

X and Y each use two PID loops running in parallel, whose outputs are summed:

1. Motor encoder PID (pid.x / pid.y): Uses D gain and FF1 for velocity damping. No I gain. Feedback from the motor-mounted encoder.
2. Linear scale PID (pid.xl / pid.yl): Uses high P and I gains for accurate position correction. Feedback from the linear scale mounted on the axis.

The outputs are summed via sum2 components:

• sum2.0: X motor PID + X linear PID
• sum2.1: Y motor PID + Y linear PID
• sum2.2: Z linear PID only (no motor encoder)

The linear scale position is used as the joint feedback (joint.N.motor-pos-fb), so LinuxCNC tracks actual table position rather than motor position.

Z-Axis Override Mechanism

The Z-axis has a special enable/disable mechanism for manual quill operation:

• A HAL logic AND gate combines two signals: z-override and z-enable
• The combined output z-enable-comb controls the Z servo PID enable and the GPIO 044 relay
• z-override defaults to TRUE at startup (CNC controls Z)
• M101 can set z-override to FALSE, disabling the Z servo so the quill can be moved manually
• M102 can set z-override back to TRUE to re-enable CNC Z control

Workaround: Because the Z servo is disabled during manual quill use, the quill position diverges from the commanded position. To prevent following-error faults, MIN_FERROR is set to 100 inches in the INI file (ideally it would be 0.2). An attempt to dynamically switch the ferror value via a mux2 component exists in the HAL but is non-functional (the output signal is not connected to the joint).

Spindle

On/off relay control only via GPIO 041. No speed control or encoder feedback. The spindle PID section in the INI exists but is effectively unused (FF0=1 with no feedback). Default spindle speed in the GUI is 500 RPM.

Pendant (XHC WHB04B-6)

Wireless pendant loaded with xhc-whb04b-6 -HsfB (HAL-only, step, filtered, 6-axis model).

Connected to joint.N.jog-* pins (not axis.x.jog-*, which GMOCCAPY does not create).

Macro Button Mapping

Macro buttons trigger MDI commands defined in the [HALUI] section of the INI:

Button	MDI Index	G-code	Action
Macro 1	01	G10 L20 P0 X[#<_x>/2.0]	Halve X coordinate
Macro 2	02	G10 L20 P0 Y[#<_y>/2.0]	Halve Y coordinate
Macro 3	--	(hardcoded)	Spindle speed increase
Macro 4	--	(hardcoded)	Spindle speed decrease
Macro 5	05	G10 L20 P0 X0	Zero X
Macro 6	06	G10 L20 P0 Y0	Zero Y
Macro 7	07	G10 L20 P0 Z0	Zero Z
Macro 8	--	(hardcoded)	Spindle direction
Macro 10	--	(hardcoded)	Toggle ABS/REL DRO
Macro 15	--	(hardcoded)	Flood coolant toggle
Macro 16	--	(hardcoded)	Mist coolant toggle

Function Buttons

Button	Action
M-Home	Home all axes (halui.home-all)
Safe-Z	MDI command 03 (debug/placeholder)
W-Home	MDI command 04 (debug/placeholder)
Probe-Z	MDI command 08 (debug/placeholder)

Feed override is connected and functional via the pendant knob.

Tool Change

Manual tool change using hal_manualtoolchange. A dialog pops up on screen prompting the operator to change the tool. Tool prepare requests are looped back (no automatic tool changer).

Axis Limits and Homing

Axis	Travel (inches)	Home Sequence
X	-24.0 to +24.0	2
Y	-12.0 to +12.0	3
Z	-4.0 to +1.0	1 (first)

NO_FORCE_HOMING = 1 is set, so the machine can be jogged and run programs without homing first.

Startup G-code

G20 G40 G90 G94 G97 G64 P0.001

• G20: Inch mode
• G40: Cancel cutter compensation
• G90: Absolute distance mode
• G94: Feed per minute
• G97: RPM mode (constant spindle speed)
• G64 P0.001: Path blending with 0.001" tolerance

E-Stop

The estop signal is looped back internally (user-enable-out -> emc-enable-in). There is no external hardware estop chain connected through LinuxCNC. The physical ESTOP button on GPIO 029 is configured as an input but not wired into the estop logic.