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

loadrt motmod [base_period_nsec=period] [servo_period_nsec=period] [traj_period_nsec=period] [key=SHMEM_KEY] [num_joints=[0-9]]

These pins and parameters are created by the realtime motmod module. This module provides a HAL interface for EMC’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.

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.

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.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.

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.

(not yet implemented) motion.analog-in-NN IN float

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

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.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 (See section, and this bit is TRUE, the feed rate is set to 0.

motion.motion-inpos OUT bit

TRUE if the machine is in position.

motion.probe-input IN bit

G38.2 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.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-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; used for G96 feed-per-revolution and constant surface speed modes.

motion.spindle-speed-out OUT float

Desired spindle speed in rotations per minute

Many of these parameters serve as debugging aids, and are subject to change or removal at any time.

axis.N.active

TRUE when this joint is active

axis.N.backlash-corr

Backlash or screw compensation raw value

axis.N.backlash-filt

Backlash or screw compensation filtered value (respecting motion limits)

axis.N.backlash-vel

Backlash or screw compensation velocity

axis.N.coarse-pos-cmd

axis.N.error

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

axis.N.f-error

The actual following error

axis.N.f-error-lim

The following error limit

axis.N.f-errored

TRUE when this joint has exceeded the following error limit

axis.N.faulted

axis.N.free-pos-cmd

The "free planner" commanded position for this joint.

axis.N.free-tp-enable

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

axis.N.free-vel-lim

The velocity limit for the free planner

axis.N.home-state

Reflects the step of homing currently taking place

axis.N.homed

TRUE if the joint has been homed

axis.N.in-position

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

axis.N.joint-vel-cmd

The joint’s commanded velocity

axis.N.kb-jog-active

axis.N.neg-hard-limit

The negative hard limit for the joint

(removed) axis.N.neg-soft-limit

The negative soft limit for the joint

axis.N.pos-hard-limit

The positive hard limit for the joint

(removed) axis.N.pos-soft-limit

The positive soft limit for the joint

axis.N.wheel-jog-active

motion-command-handler.time

motion-command-handler.tmax

motion-controller.time

motion-controller.tmax

motion.coord-error

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

motion.coord-mode

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

motion.current-vel

motion.debug-*

These values are used for debugging purposes.

motion.in-position

Same as the pin motion.motion-inpos

motion.motion-enabled

TRUE when motion is enabled

motion.on-soft-limit

motion.program-line

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

motion.servo.overruns

By noting large differences between successive values of motion.servo.last-period, the motion controller can determine that there has probably been a failure to meet its timing constraints. Each time such a failure is detected, this value is incremented.

motion.teleop-mode

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

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 emc motion controller

This manual page is horribly incomplete.

iocontrol(1)