Driving 2 steppers on the same axis.

Hello,

I am an inexperienced Linux user working on a gantry style CNC. The machine is essentially mechanically completed, but there are problems that I am trying to work out by reading in this forum. However, I have read and worked on trying to get the (two) Y axes to work together and admit defeat so far. X and Z work fine, I think, and home okay. But I am a failure on Y.

Just updated to 2.7.3 this morning and worked on the 'probe_parport' problem but made no other progress.

Following are the .ini and .hal files Probably some obvious and foolish mistake(s) but it is beyond me and I would certainly appreciate help.
I have other problems but would like to get over this hurdle.

Joe

# Generated by stepconf 1.1 at Sat Dec 19 15:54:51 2015
# If you make changes to this file, they will be
# overwritten when you run stepconf again

[EMC]
MACHINE = mygantry
DEBUG = 0

[DISPLAY]
DISPLAY = axis
EDITOR = gedit
POSITION_OFFSET = RELATIVE
POSITION_FEEDBACK = ACTUAL
ARCDIVISION = 64
GRIDS = 10mm 20mm 50mm 100mm 1in 2in 5in 10in
MAX_FEED_OVERRIDE = 1.2
MIN_SPINDLE_OVERRIDE = 0.5
MAX_SPINDLE_OVERRIDE = 1.2
DEFAULT_LINEAR_VELOCITY = 0.10
MIN_LINEAR_VELOCITY = 0
MAX_LINEAR_VELOCITY = 1.00
INTRO_GRAPHIC = linuxcnc.gif
INTRO_TIME = 5
PROGRAM_PREFIX = /home/norbert/linuxcnc/nc_files
INCREMENTS = .1in .05in .01in .005in .001in .0005in .0001in
PYVCP = custompanel.xml

[FILTER]
PROGRAM_EXTENSION = .png,.gif,.jpg Greyscale Depth Image
PROGRAM_EXTENSION = .py Python Script
png = image-to-gcode
gif = image-to-gcode
jpg = image-to-gcode
py = python

[TASK]
TASK = milltask
CYCLE_TIME = 0.010

[RS274NGC]
PARAMETER_FILE = linuxcnc.var

[EMCMOT]
EMCMOT = motmod
COMM_TIMEOUT = 1.0
COMM_WAIT = 0.010
BASE_PERIOD = 100000
SERVO_PERIOD = 1000000

[HAL]
HALUI = halui
HALFILE = mygantry.hal
HALFILE = custom.hal
POSTGUI_HALFILE = custom_postgui.hal

[HALUI]
# add halui MDI commands here (max 64)

[TRAJ]
AXES = 3
COORDINATES = X Y Z
LINEAR_UNITS = inch
ANGULAR_UNITS = degree
CYCLE_TIME = 0.010
DEFAULT_VELOCITY = 0.10
MAX_VELOCITY = 1.00

[EMCIO]
EMCIO = io
CYCLE_TIME = 0.100
TOOL_TABLE = tool.tbl

[AXIS_0]
TYPE = LINEAR
HOME = 0.0
MAX_VELOCITY = 1.0
MAX_ACCELERATION = 30.0
STEPGEN_MAXACCEL = 37.5
SCALE = 6400.0
FERROR = 0.05
MIN_FERROR = 0.01
MIN_LIMIT = -0.01
MAX_LIMIT = 8.0
HOME_OFFSET = 0.000000
HOME_SEARCH_VEL = 0.100000
HOME_LATCH_VEL = -0.078125
HOME_IGNORE_LIMITS = YES
HOME_SEQUENCE = 1

[AXIS_1]
TYPE = LINEAR
HOME = 0.0
MAX_VELOCITY = 1.0
MAX_ACCELERATION = 30.0
STEPGEN_MAXACCEL = 37.5
SCALE = 6400.0
FERROR = 0.05
MIN_FERROR = 0.01
MIN_LIMIT = -0.01
MAX_LIMIT = 8.0
HOME_OFFSET = 0.000000
HOME_SEARCH_VEL = 0.100000
HOME_LATCH_VEL = -0.078125
HOME_IGNORE_LIMITS = YES
HOME_SEQUENCE = 2

[AXIS_2]
TYPE = LINEAR
HOME = -0.0
MAX_VELOCITY = 1.0
MAX_ACCELERATION = 30.0
STEPGEN_MAXACCEL = 37.5
SCALE = 6400.0
FERROR = 0.05
MIN_FERROR = 0.01
MIN_LIMIT = -0.01
MAX_LIMIT = 6.0
HOME_OFFSET = 0.000000
HOME_SEARCH_VEL = -0.100000
HOME_LATCH_VEL = 0.078125
HOME_IGNORE_LIMITS = YES
HOME_SEQUENCE = 0


# Generated by stepconf 1.1 at Sat Dec 19 15:54:51 2015
# If you make changes to this file, they will be
# overwritten when you run stepconf again
loadrt gantrykins coordinates=XYZY
loadrt [EMCMOT]EMCMOT base_period_nsec=[EMCMOT]BASE_PERIOD servo_period_nsec=[EMCMOT]SERVO_PERIOD num_joints=[TRAJ]AXES
#loadrt probe_parport after 2.7.3 upgrade
loadrt hal_parport cfg="0x378 out"
setp parport.0.reset-time 2000
loadrt stepgen step_type=0,0,0

addf parport.0.read base-thread
addf stepgen.make-pulses base-thread
addf parport.0.write base-thread
addf parport.0.reset base-thread

addf stepgen.capture-position servo-thread
addf motion-command-handler servo-thread
addf motion-controller servo-thread
addf stepgen.update-freq servo-thread
net spindle-cmd <= motion.spindle-speed-out
net spindle-at-speed => motion.spindle-at-speed

net estop-out => parport.0.pin-01-out
net xstep => parport.0.pin-02-out
setp parport.0.pin-02-out-reset 1
net xdir => parport.0.pin-03-out
net ystep => parport.0.pin-04-out
setp parport.0.pin-04-out-reset 1
net ydir => parport.0.pin-05-out
net zstep => parport.0.pin-06-out
setp parport.0.pin-06-out-reset 1
net zdir => parport.0.pin-07-out
net xstep => parport.0.pin-08-out
setp parport.0.pin-08-out-reset 1
net xdir => parport.0.pin-09-out
net max-x <= parport.0.pin-10-in
net min-home-x <= parport.0.pin-11-in
net min-home-y <= parport.0.pin-12-in
net min-home-z <= parport.0.pin-13-in

setp stepgen.0.position-scale [AXIS_0]SCALE
setp stepgen.0.steplen 1
setp stepgen.0.stepspace 0
setp stepgen.0.dirhold 17200
setp stepgen.0.dirsetup 17200
setp stepgen.0.maxaccel [AXIS_0]STEPGEN_MAXACCEL
net xpos-cmd axis.0.motor-pos-cmd => stepgen.0.position-cmd
net xpos-fb stepgen.0.position-fb => axis.0.motor-pos-fb
net xstep <= stepgen.0.step
net xdir <= stepgen.0.dir
net xenable axis.0.amp-enable-out => stepgen.0.enable
net min-home-x => axis.0.home-sw-in
net min-home-x => axis.0.neg-lim-sw-in
net max-x => axis.0.pos-lim-sw-in

setp stepgen.1.position-scale [AXIS_1]SCALE
setp stepgen.1.steplen 1
setp stepgen.1.stepspace 0
setp stepgen.1.dirhold 17200
setp stepgen.1.dirsetup 17200
setp stepgen.1.maxaccel [AXIS_1]STEPGEN_MAXACCEL
net ypos-cmd axis.1.motor-pos-cmd => stepgen.1.position-cmd
net ypos-fb stepgen.1.position-fb => axis.1.motor-pos-fb
net ystep <= stepgen.1.step
net ydir <= stepgen.1.dir
net yenable axis.1.amp-enable-out => stepgen.1.enable
net min-home-y => axis.1.home-sw-in
net min-home-y => axis.1.neg-lim-sw-in

setp stepgen.2.position-scale [AXIS_2]SCALE
setp stepgen.2.steplen 1
setp stepgen.2.stepspace 0
setp stepgen.2.dirhold 17200
setp stepgen.2.dirsetup 17200
setp stepgen.2.maxaccel [AXIS_2]STEPGEN_MAXACCEL
net zpos-cmd axis.2.motor-pos-cmd => stepgen.2.position-cmd
net zpos-fb stepgen.2.position-fb => axis.2.motor-pos-fb
net zstep <= stepgen.2.step
net zdir <= stepgen.2.dir
net zenable axis.2.amp-enable-out => stepgen.2.enable
net min-home-z => axis.2.home-sw-in
net min-home-z => axis.2.neg-lim-sw-in

net estop-out <= iocontrol.0.user-enable-out
net estop-out => iocontrol.0.emc-enable-in

loadusr -W hal_manualtoolchange
net tool-change iocontrol.0.tool-change => hal_manualtoolchange.change
net tool-changed iocontrol.0.tool-changed <= hal_manualtoolchange.changed
net tool-number iocontrol.0.tool-prep-number => hal_manualtoolchange.number
net tool-prepare-loopback iocontrol.0.tool-prepare => iocontrol.0.tool-prepared

Thank you for your prompt response.

Yes, only one stepper is moving.

As to how I want to do it, I tried to follow what I have read in previous posts and have attempted to implement gantrykins by editing the .hal file entry that implemented trivikins (hope that is the correct spelling). to gantrykins and then editing other lines to account for the hardware on the machine. There are various posts on this method and I read through all of them that I could find and tried to work those out.

I am open to any suggestions.

By the way, drive is screw driven with two screws for the Y axis.

Thanks again.

Joe

If you are not using separate home / limits switches for the 2 y axis you could just use a regular xyz configuration.
As Andy pointed out there are many way to do and split the signal. For example...
In your configuration file you have...Which connects the step and direction pins to the 2 parallel port pins for the y drive.
Add the correct parallel port pins for the second y drive to ystep and ydir in the same manner.
You may need to invert the direction signal to get the motor turning the correct direction. or swap a pair of wires on the stepper motor (with the power off!).

Rick G

Many thanks to Andypugh and RIck G as, with their suggestions, now it is working and I am on to other problems.


Joe