On 2012-03-24, Dennis wrote:
I've got a problem I cant seem to sort on my little DIY CNC router, my limit
switches don't work!
1) I've installed limit / end of travel switches on the x,y & z axes.
2) The switches are wired in series and wired to input 10 and enabled.
3) The switches are all normally closed, the input goes hi when switches
operate.
4) In diagnostics I can operate any of the switches manually & the program
senses it ok.
But.... when I jog any axis or run some code to move an axis, operating any
of the switches does nothing. I expected the motors to be disabled when I
operated a switch.
I've tried inverting the active level of the switches (ie hi/low active) and
have tried changing just about every other setting.
I've watched a couple of the mach3 videos (which have taught me a lot) but
cannot find out what the problem is.
I don't know Mach3, and it is probably a configuration in there
somewhere. Something along the lines of "When you sense this -- STOP!",
instead of "When you sense this, make a note in a logfile or on the
screen and keep on truckin'. :-)
Or is there a "E-stop override" in Mach3 somewhere? Could this
be engaged?
But first -- are you using steppers or servos? Steppers stop as
soon as the computer stops talking to them. Servos keep moving at the
last commanded speed until the computer says to change to zero inches
per second (0 V command input to the servo amp).
And in either case, the stepper driver or the servo amp should
have a separate input to inhibit motion. This really should be
connected. (Some servo amps have separate inputs to inhibit motion in
the two directions, so you can have two limit switches, and still be
able to feed it commands to back it off the limit switch. It would
proably be easy enough to add those to stepper drivers too, if they
don't already exist.) The "stop in any direction" input connects to
the E-stop red mushroom button.
Good Luck,
DoN.
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