NAME

       gantry - LinuxCNC HAL component for driving multiple joints from a single axis.

SYNOPSIS

       loadrt gantry [count=N|names=name1[,name2...]] [personality=P1,P2,...]

DESCRIPTION

       Drives multiple physical motors (joints) from a single axis input

       The `personality' value is the number of joints to control.  Two is typical, but up to seven is supported
       (a three joint setup has been tested with hardware).

       All  controlled  joints  track  the commanded position (with a per-joint offset) unless in the process of
       homing.  Homing is when the commanded position is moving towards the homing switches  (as  determined  by
       the  sign  of  search-vel) and the joint home switches are not all in the same state.  When the system is
       homing and a joint home switch activates, the command value sent to that joint is "frozen" and the  joint
       offset  value  is updated instead.  Once all home switches are active, there are no more adjustments made
       to the offset values and all joints run in lock-step once more.

       For best results, set HOME_SEARCH_VEL and HOME_LATCH_VEL to the same direction and as slow as  practical.
       When  a  joint  home  switch  trips, the commanded velocity will drop immediately from HOME_SEARCH_VEL to
       zero, with no limit on acceleration.

FUNCTIONS

       gantry.N.read (requires a floating-point thread)
              Update position-fb and home/limit outputs based on joint values.

       gantry.N.write (requires a floating-point thread)
              Update joint pos-cmd outputs based on position-cmd in.

PINS

       gantry.N.joint.MM.pos-cmd float out (MM=00..personality)
              Per-joint commanded position

       gantry.N.joint.MM.pos-fb float in (MM=00..personality)
              Per-joint position feedback

       gantry.N.joint.MM.home bit in (MM=00..personality)
              Per-joint home switch

       gantry.N.joint.MM.offset float out (MM=00..personality)
              (debugging) Per-joint offset value, updated when homing.

       gantry.N.position-cmd float in
              Commanded position from motion

       gantry.N.position-fb float out
              Position feedback to motion

       gantry.N.home bit out
              Combined home signal, true if all joint home inputs are true.

       gantry.N.limit bit out
              Combined limit signal, true if any joint home input is true.

       gantry.N.search-vel float in
              HOME_SEARCH_VEL from INI file

AUTHOR

       Charles Steinkuehler

LICENSE

       GPL

LinuxCNC Documentation                             2025-08-07                                          GANTRY(9)