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Integration of Motionsystem

Splicer uses LinuxCNC for motion control. This chapter provides an overview of how the machine is defined and operated through the splicer.ini configuration file. The .ini file describes axis definitions, joint mappings, kinematics, HAL files, timing, and IO assignments.

The full LinuxCNC configuration for Splicer is available on GitHub:
Splicer LinuxCNC Config Repository

splicer.ini Overview

DRIVER = hm2_eth
IPADDRESS = "10.10.10.10"
BOARD = 7i96
STEPGENS = 9

Splicer uses a Mesa 7i96 board over Ethernet (hm2_eth) with a daisychained 7i78 for a total of 9 step generators (1 per joint).

[KINS]

KINEMATICS = trivkins coordinates=XYZZCVBAU
JOINTS = 9

Splicer mostly uses trivial kinematics, with the exception of axis A und B that go through a HAL CoreXY conversion and Z that is driven by two joints / motors.

Axis Configuration

Each axis has:

  • MIN / MAX limits in mm or degrees
  • Velocity and acceleration
  • PID and stepgen tuning
  • Homing logic

Example:

[AXIS_N]
MIN_LIMIT = -254
MAX_LIMIT = 254
MAX_VELOCITY = 200
MAX_ACCELERATION = 400

Defines limits and motion constraints for the X axis.

Joint Configuration

Splicer has 9 joints, each tied to a unique physical axis:

  • JOINT_0: X (lateral sample movement)
  • JOINT_1: Y (depth sample movement)
  • JOINT_2 to JOINT_3: Z Lift (dual motors)
  • JOINT_4: C (rotation of sample)
  • JOINT_5: V (focus rail)
  • JOINT_6: B (vertical optical shift, coreXY)
  • JOINT_7: A (horizontal optical shift, coreXY)
  • JOINT_8: U (sensor rotation)
Kinematics: CoreXY (A and B Axis) & Z-Split

The CoreXY kinematic conversion of A and B axis is handled via:

HALFILE = corexy_by_hal.hal

This HAL file handles the translation from A/B movement to the AB-motor configuration typical of CoreXY machines. The dual-Z motor setup (Z0 and Z1) allows synchronized lifting of the camera platform.

Inputs & Outputs

[INPUTS]

INPUT_0 = Home
INPUT_JOINT_0 = 0
...
INPUT_8 = Home
INPUT_JOINT_8 = 8

Maps home switches to individual joints.

[OUTPUTS]

OUTPUT_0 = Digital Out 0
OUTPUT_1 = Digital Out 1

Outputs are used to trigger external systems (M62/M63 line triggers to the framegrabber).

Important Notes

  • Servo period and step timings (STEPLEN, STEPSPACE, etc.) need to be tuned for the specific stepper drivers used in Splicer.
  • Inverse time feedrate (G93) is used during capture (see G-code specs), requiring stable timing and precision movement synchronization.
  • Homing sequence is designed to prevent axis collisions. Do only change if you know what you are doing.

Development Status

The LinuxCNC integration of Splicer is fully functional and has been tested in live capture. The configuration is modular, and each HAL file corresponds to a subsystem (motion, CoreXY translation, IO extensions).