motmod configuration

motmod is the LinuxCNC motion module. In NoHAL, the motmod settings are stored in the project and used in two places:

• to export the loadrt motmod ... arguments
• to keep the System sheet’s motmod-managed nodes aligned with the configured instance counts

Where It Lives In The App

Motmod settings are edited in Project Settings > motmod.

Stored Settings

NoHAL stores these motmod-related values in the project:

• num_joints
• num_dio
• num_aio
• num_spindles
• num_misc_error
• traj_period_nsec (0 means “use servo period”)

Derived From HAL Threads

Some motmod arguments are derived from Project Settings > HAL Threads:

• servo_period_nsec comes from the servo-thread period
• base_period_nsec comes from the base-thread period
• base_thread_fp comes from the base-thread float mode (fp/nofp)

If the project does not define a servo-thread, export omits the servo/traj period arguments for motmod and emits a warning.

System HAL projection (System sheet)

NoHAL maintains a motmod-managed projection on the System sheet. When you change motmod settings, the expected set of System-sheet nodes can change.

The projection covers these motmod-managed families:

• motion
• axis
• joint (LinuxCNC 2.8+)
• spindle (LinuxCNC 2.8+)

The counts and instance names are derived from the motmod settings. For example:

• motion is always present as motion
• joint nodes are joint.0 .. joint.(num_joints-1)
• spindle nodes are spindle.0 .. spindle.(num_spindles-1)

The motion node also has managed instance configuration values that mirror selected motmod settings (for example num_dio, num_aio, and num_misc_error on LinuxCNC versions that support it). Those values are used to expand the motion.* pin set.

The motmod tab shows whether the System HAL projection is in sync. The Sync now action reconciles the System sheet by adding/removing/adopting/updating motmod-managed nodes and ensuring the matching system component definitions exist.