MOTION

NAME
SYNOPSIS
DESCRIPTION
PINS
DEBUGGING PINS
PARAMETERS
FUNCTIONS
BUGS
SEE ALSO

NAME

motion − accepts NML motion commands, interacts with HAL in realtime

SYNOPSIS

loadrt motmod [base_period_nsec=period] [base_thread_fp=0 or 1] [servo_period_nsec=period] [traj_period_nsec=period] [num_joints=[0-9]] ([num_dio=[1-64]] [num_aio=[1-64]])

DESCRIPTION

By default, the base thread does not support floating point. Software stepping, software encoder counting, and software pwm do not use floating point. base_thread_fp can be used to enable floating point in the base thread (for example for brushless DC motor control).

These pins and parameters are created by the realtime motmod module. This module provides a HAL interface for LinuxCNC’s motion planner. Basically motmod takes in a list of waypoints and generates a nice blended and constraint-limited stream of joint positions to be fed to the motor drives.

Optionally the number of Digital I/O is set with num_dio. The number of Analog I/O is set with num_aio. The default is 4 each.

Pin names starting with "axis" are actually joint values, but the pins and parameters are still called "axis.N". They are read and updated by the motion-controller function.

PINS

axis.N.amp-enable-out OUT BIT

TRUE if the amplifier for this joint should be enabled

axis.N.amp-fault-in IN BIT

Should be driven TRUE if an external fault is detected with the amplifier for this joint

axis.N.home-sw-in IN BIT

Should be driven TRUE if the home switch for this joint is closed

axis.N.homing OUT BIT

TRUE if the joint is currently homing

axis.N.index-enable IO BIT

Should be attached to the index-enable pin of the joint’s encoder to enable homing to index pulse

axis.N.is-unlocked IN BIT

If the axis is a locked rotary the unlocked sensor should be connected to this pin

axis.N.jog-counts IN S32

Connect to the "counts" pin of an external encoder to use a physical jog wheel.

axis.N.jog-enable IN BIT

When TRUE (and in manual mode), any change to "jog-counts" will result in motion. When false, "jog-counts" is ignored.

axis.N.jog-scale IN FLOAT

Sets the distance moved for each count on "jog-counts", in machine units.

axis.N.jog-vel-mode IN BIT

When FALSE (the default), the jogwheel operates in position mode. The axis will move exactly jog-scale units for each count, regardless of how long that might take. When TRUE, the wheel operates in velocity mode - motion stops when the wheel stops, even if that means the commanded motion is not completed.

axis.N.joint-pos-cmd OUT FLOAT

The joint (as opposed to motor) commanded position. There may be several offsets between the joint and motor coordinates: backlash compensation, screw error compensation, and home offsets.

axis.N.joint-pos-fb OUT FLOAT

The joint feedback position. This value is computed from the actual motor position minus joint offsets. Useful for machine visualization.

axis.N.motor-pos-cmd OUT FLOAT

The commanded position for this joint.

axis.N.motor-pos-fb IN FLOAT

The actual position for this joint.

axis.N.neg-lim-sw-in IN BIT

Should be driven TRUE if the negative limit switch for this joint is tripped.

axis.N.pos-lim-sw-in IN BIT

Should be driven TRUE if the positive limit switch for this joint is tripped.

axis.N.unlock OUT BIT

TRUE if the axis is a locked rotary and a move is commanded.

motion.adaptive-feed IN FLOAT

When adaptive feed is enabled with M52 P1, the commanded velocity is multiplied by this value. This effect is multiplicative with the NML-level feed override value and motion.feed-hold.

motion.analog-in-NN IN FLOAT

These pins are used by M66 Enn wait-for-input mode.

motion.analog-out-NN OUT FLOAT

These pins are used by M67-68.

motion.coord-error OUT BIT

TRUE when motion has encountered an error, such as exceeding a soft limit

motion.coord-mode OUT BIT

TRUE when motion is in "coordinated mode", as opposed to "teleop mode"

motion.current-vel OUT FLOAT

Current cartesian velocity

motion.digital-in-NN IN BIT

These pins are used by M66 Pnn wait-for-input mode.

motion.digital-out-NN OUT BIT

These pins are controlled by the M62 through M65 words.

motion.distance-to-go OUT FLOAT

Distance remaining in the current move

motion.enable IN BIT

If this bit is driven FALSE, motion stops, the machine is placed in the "machine off" state, and a message is displayed for the operator. For normal motion, drive this bit TRUE.

motion.feed-hold IN BIT

When Feed Stop Control is enabled with M53 P1, and this bit is TRUE, the feed rate is set to 0.

motion.feed-inhibit IN BIT

When this pin is TRUE, machine motion is inhibited (this includes jogs, programmed feeds, and programmed rapids, aka traverse moves).

If the machine is performing a spindle synchronized move when this pin goes TRUE, the spindle synchronized motion will finish, and any following moves will be inhibited (this is to prevent damage to the machine, the tool, or the work piece).

If the machine is in the middle of a (non-spindle synchronized) move when this pin goes TRUE, the machine will decelerate to a stop at the maximum allowed acceleration rate.

Motion resumes when this pin goes FALSE.

motion.in-position OUT BIT

TRUE if the machine is in position (ie, not currently moving towards the commanded position).

motion.probe-input IN BIT

G38.x uses the value on this pin to determine when the probe has made contact. TRUE for probe contact closed (touching), FALSE for probe contact open.

motion.program-line OUT S32
motion.requested-vel
OUT FLOAT

The requested velocity with no adjustments for feed override

motion.spindle-at-speed IN BIT

Motion will pause until this pin is TRUE, under the following conditions: before the first feed move after each spindle start or speed change; before the start of every chain of spindle-synchronized moves; and if in CSS mode, at every rapid->feed transition.

motion.spindle-brake OUT BIT

TRUE when the spindle brake should be applied

motion.spindle-forward OUT BIT

TRUE when the spindle should rotate forward

motion.spindle-index-enable I/O BIT

For correct operation of spindle synchronized moves, this signal must be hooked to the index-enable pin of the spindle encoder.

motion.spindle-inhibit IN BIT

When TRUE, the spindle speed is set and held to 0.

motion.spindle-on OUT BIT

TRUE when spindle should rotate

motion.spindle-reverse OUT BIT

TRUE when the spindle should rotate backward

motion.spindle-revs IN FLOAT

For correct operation of spindle synchronized moves, this signal must be hooked to the position pin of the spindle encoder.

motion.spindle-speed-in IN FLOAT

Actual spindle speed feedback in revolutions per second; used for G96 (constant surface speed) and G95 (feed per revolution) modes.

motion.spindle-speed-out OUT FLOAT

Desired spindle speed in rotations per minute

motion.spindle-speed-out-abs OUT FLOAT

Desired spindle speed in rotations per minute, always positive regardless of spindle direction.

motion.spindle-speed-out-rps OUT float

Desired spindle speed in rotations per second

motion.spindle-speed-out-rps-abs OUT float

Desired spindle speed in rotations per second, always positive regardless of spindle direction.

motion.spindle-orient-angle OUT FLOAT

Desired spindle orientation for M19. Value of the M19 R word parameter plus the value of the [RS274NGC]ORIENT_OFFSET ini parameter.

motion.spindle-orient-mode OUT BIT

Desired spindle rotation mode. Reflects M19 P parameter word.

motion.spindle-orient OUT BIT

Indicates start of spindle orient cycle. Set by M19. Cleared by any of M3,M4,M5. If spindle-orient-fault is not zero during spindle-orient true, the M19 command fails with an error message.

motion.spindle-is-oriented IN BIT

Acknowledge pin for spindle-orient. Completes orient cycle. If spindle-orient was true when spindle-is-oriented was asserted, the spindle-orient pin is cleared and the spindle-locked pin is asserted. Also, the spindle-brake pin is asserted.

motion.spindle-orient-fault IN S32

Fault code input for orient cycle. Any value other than zero will cause the orient cycle to abort.

motion.spindle-locked OUT BIT

Spindle orient complete pin. Cleared by any of M3,M4,M5.

motion.teleop-mode OUT bit
motion.tooloffset.x
OUT FLOAT
motion.tooloffset.y
OUT FLOAT
motion.tooloffset.z
OUT FLOAT
motion.tooloffset.a
OUT FLOAT
motion.tooloffset.b
OUT FLOAT
motion.tooloffset.c
OUT FLOAT
motion.tooloffset.u
OUT FLOAT
motion.tooloffset.v
OUT FLOAT
motion.tooloffset.w
OUT FLOAT

Current tool offset in all 9 axes.

DEBUGGING PINS

Many of the pins below serve as debugging aids, and are subject to change or removal at any time.
axis.
N.active OUT BIT

TRUE when this joint is active

axis.N.backlash-corr OUT FLOAT

Backlash or screw compensation raw value

axis.N.backlash-filt OUT FLOAT

Backlash or screw compensation filtered value (respecting motion limits)

axis.N.backlash-vel OUT FLOAT

Backlash or screw compensation velocity

axis.N.coarse-pos-cmd OUT FLOAT
axis.
N.error OUT BIT

TRUE when this joint has encountered an error, such as a limit switch closing

axis.N.f-error OUT FLOAT

The actual following error

axis.N.f-error-lim OUT FLOAT

The following error limit

axis.N.f-errored OUT BIT

TRUE when this joint has exceeded the following error limit

axis.N.faulted OUT BIT
axis.
N.free-pos-cmd OUT FLOAT

The "free planner" commanded position for this joint.

axis.N.free-tp-enable OUT BIT

TRUE when the "free planner" is enabled for this joint

axis.N.free-vel-lim OUT FLOAT

The velocity limit for the free planner

axis.N.homed OUT BIT

TRUE if the joint has been homed

axis.N.in-position OUT BIT

TRUE if the joint is using the "free planner" and has come to a stop

axis.N.joint-vel-cmd OUT FLOAT

The joint’s commanded velocity

axis.N.kb-jog-active OUT BIT
axis.
N.neg-hard-limit OUT BIT

The negative hard limit for the joint

axis.N.pos-hard-limit OUT BIT

The positive hard limit for the joint

axis.N.wheel-jog-active OUT BIT
motion.motion-enabled
OUT BIT
motion.motion-type
OUT S32

These values are from src/emc/nml_intf/motion_types.h

0: Idle (no motion)

1: Traverse

2: Linear feed

3: Arc feed

4: Tool change

5: Probing

6: Rotary axis indexing

motion.on-soft-limit OUT BIT
motion.program-line
OUT S32
motion.teleop-mode
OUT BIT

TRUE when motion is in "teleop mode", as opposed to "coordinated mode"

PARAMETERS

Many of the parameters serve as debugging aids, and are subject to change or removal at any time.
motion-command-handler.time
motion-command-handler.tmax
motion-controller.time
motion-controller.tmax

Show information about the execution time of these HAL functions in CPU cycles

motion.debug-*

These values are used for debugging purposes.

motion.servo.last-period

The number of CPU cycles between invocations of the servo thread. Typically, this number divided by the CPU speed gives the time in seconds, and can be used to determine whether the realtime motion controller is meeting its timing constraints

FUNCTIONS

Generally, these functions are both added to the servo-thread in the order shown.
motion-command-handler

Processes motion commands coming from user space

motion-controller

Runs the LinuxCNC motion controller

BUGS

This manual page is horribly incomplete.

SEE ALSO

iocontrol(1)