Mach3,home sw. Erratic Behavior

[rcpilot82]

I have just finished my router and was setting up the home/limit switches when I ran into this issue. first the setup; mach3 running on laptop w/parallel port. 3 axis router with hobbycnc kit. Now the issue, I find that with the steppers turned off the home/limit switches work fine. when the steppers are turned on the "leds" on the diagnostics display in mach start intermittenly flashing (as if a switch is being triggered) not allowing me to complete the setup of the switches. i am running shielded 20 gage wire, all switches are wired correctly (series) and I have even gone as far as soldering all the terminals together to no avail. I am stumped at this one and need help! any ideas?

[TOTALLYRC]

Originally Posted by rcpilot82 I have just finished my router and was setting up the home/limit switches when I ran into this issue. first the setup; mach3 running on laptop w/parallel port. 3 axis router with hobbycnc kit. Now the issue, I find that with the steppers turned off the home/limit switches work fine. when the steppers are turned on the "leds" on the diagnostics display in mach start intermittenly flashing (as if a switch is being triggered) not allowing me to complete the setup of the switches. i am running shielded 20 gage wire, all switches are wired correctly (series) and I have even gone as far as soldering all the terminals together to no avail. I am stumped at this one and need help! any ideas?

Make sure that the wire shield is grounded at the controller end only.

Also go into the general configuration page and increase the debounce setting. This will increase the time a signal has to be active before Mach will recognize it as valid.

Mike

[rcpilot82]

Originally Posted by TOTALLYRC Make sure that the wire shield is grounded at the controller end only. Also go into the general configuration page and increase the debounce setting. This will increase the time a signal has to be active before Mach will recognize it as valid. Mike

Great ideas, didn't solve my issue though I ruled out the computer being a possibility by trying a desktop pc, same thing. I am sooooo close to cutting parts out on this thing but I really want the home/limit switches to work as i am a newb. any other suggestions?? I am all ears!

[wyldesyde007]

what type of switches are you using no/ nc? and how did you wire them? I used a cheapo radio shack push button switch that is a nc switch that way if a wire were to break or become mysteriously detached it would stop the machine. I used plain old speaker wire to connect them.

[wyldesyde007]

I did find that running my cnc from a laptop (which I did for a while before I built a dedicated pc for it) made it run slow, once I connected it to a desktop pc I had to re-tune the steppers as they were being run faster than when it was hooked to the laptop.

[wyldesyde007]

You might try connecting only 1 switch to the limit switch outs on your board then watch the diagnostic page in mach as you depress the switch and see if the light blinks on and off as you push it. If it does then you know the board is wired right and you may have a faulty switch, keep checking the switches 1 by 1.

[ger21]

Did you try around 5000 for the debounce?

[rcpilot82]

Thanks for the ideas guys, yeah I tried everything from 100 to 9999 on the debounce. switches are all NC and wired in series. with the steppers off I verifies that all the switches are operational, and verified this with a meter without the wires connected. I started out with just speaker hook up wire for the switches and then re-wired with the shielded wires after I discovered this. I now have a desktop pc hooked up to the router and same result. what now??

[woffler]

check with hobby cnc and see what they have to say as to the wiring of the switches some bo boards will only run home switches in the normally open position i know it sounds nuts but it depends on the board manufacturer.

[123CNC]

What type of limit switches? Optical, mechanical? If mechanical, are the plunger or arm-roller actuated? How close is your trip point or switch engagement when this occurs, or are you nowhere in the ballpark physically when this happens?

When you turn your steppers on do your limits on the diagnostics page flicker with the steppers at rest or during motion or both?

If you are seeing intermittent signals with steppers on at rest, how difficult to dismount your limit switches or just the wiring and move to a different orientation and monitor the flickering status (sweep that long antenna for poorer reception)? Are your limit switch wires ran side by side with your stepper drive wires or other power lines? Are your stepper motor leads shielded?

How and where did you terminate your limit switch shielding? Where is your panel or BOB ground in relationship to this point?

[rcpilot82]

Switches are mechanical,arm roller type. I am nowhere near the switch when the trips happen. Yes when the steppers are powered up the limits lights flicker, both at rest and in motion. I have relocated as much wire as posible and it makes no difference. all wires are shielded both stepper and switches. there is no BOB, all the connections are on teh hobby cnc pro board. here is something funny i noticed just now. I removed the wires from the y and z axis switches from the circuits and my stepper "hiss" went to about half of what it was so i cut the signal input wire on pin #11, result was broken circuit "duh" but stepper hiss went down a bit. when I removed the ground wire my stepper hiss went almost completely away!? how can the limit switches affect stepper hiss? another wierd observation was with ONLY the ground wire hooked up to the switches, when a switch is pressed the "tone" of the stepper hiss would change?? I am stumped

[Claude Boudreau]

I had a big problem when I first build my cnc router I was hearing an intermittent hiss in my stepper and loosing control of the current enough to burn board , solved the problem insulating the computer ground from my control box ground, with a simple piece of acrylic to mount the db25 connector.Before I did this when I connected the ground of the shield wire I heard noise in my motor. Someone explained to me that was due to induced voltage on V.ref line . Hope this help.