limit switch triggered issue

[15mgtar]

I got this problem of limit switch has been triggered issue that I never had any problem with it before. I am not really sure where to start my troubleshooting any body have suggestion?

[mactec54]

Hi 15Mgtar

Are you using shielded cables if not you need them & if you have shielded cable are they grounded correctly (one end only) for each switch

[15mgtar]

I don't use shielded cables, what's the size of shielded cables do I need for my limit switches? 22 guage of shielded cables will do (because they are kinda expensive and they come in as twisted shielded cable not a single twisted cables)
They are grounded correctly I think.

[15mgtar]

I've got a question all.
I've got Belden-M 8760 shielded cables do I need to ground the shield or just leave it alone as is?

[jeffery71]

You would normally ground the shield at one end. That being said I have never grounded mine and have no problems. You said you have not had problems with the limit switches before wich leads me to believe its not a problem with shielding.

Is the limit switch tripped all the time now? If so then I think you should get out an electrical meter and start checking the wires and the switches if you have not already. I had one wire get loose where it connected to the switch.

If it is intermiten then it may be the shielding. But it could still be a loose wire some place that is causing the problem. When the machine moves or vibrates it would wiggle the wire and cause the trip.

Are your switches wired normally closed? If so disconnect them at your breakout board and hook your ohm meter to them. Find out if you are getting continuity through the wires.

Jeff T.

http://3dcarvestudio.com

[Chris64]

Originally Posted by mactec54 Hi 15Mgtar Are you using shielded cables if not you need them & if you have shielded cable are they grounded correctly (one end only) for each switch

I know this is a dumb question, but is there any easy way around this? I'm having the same problem it appears. It's showing always closed regardless of the limit switch state. On a meter it's working perfectly. If I disconnect one the lines from the board it shows an open circuit as it should. But when all connected it won't detect an open switch.

Mine also worked originally (when just partially setup), but has only stopped working now that I've completed the setup (and of course added more components and wires).

In my case rewiring isn't a realistic option. I could potentially use the wiring to throw a relay and run a shielded wire from that, but would that work (given it's sensitivity to interference)? Wouldn't it be possible to maybe add a resistor to ground to remove this small interference or maybe a cap? Or is it something else. I'll admit, I probably know just enough to be very dangerous. But at least I know I don't want to get started until my limit switches are working properly

NOTE: I just decided to try a cap across the line and it appears to solve the problem. It's a 47mfd cap. It does cause a small delay in detecting it - not huge - but I can quickly tap the switch and it won't detect it. Realistically for me this is probably acceptable.

[schwinndk]

Try ajusting the Debaunce Interval under general settings in Mach3. Set it to 1000, and work it down from there. My limit switches triggered now and then when running the program, so I had to ajust it up even though I use shielded cabels.
Kim