Switches and wiring

[T_Brown]

I finally have my first gantry style router up and running and am starting to focus on the wiring and fine tuning of it. I have done some searching on the zone but can't find many tips or info about wiring. One of my biggest questions is in regards to wiring the home/limit switches. I plan to have 2 limits on each axis with one of the limits also acting as a home switch. Should these be wired in series or parralel? Each axis will be connected to its own input on my G540, whats the best way to splice these wires to eachother? Terminal blocks inside my enclosure? Any thoughts, tips or just pictures of how you wired your machine would be very helpful.

I am also looking for some switches. I am planning on using some of the concepts from Phomann's wiring diagram including the enable switch but am not sure what i should be looking for. Obviously, electronics are not my strong suit. I am also thinking i would like to add a push button switch to control my router, just thinking i will make a switched outlet that the router plugs into, but would like a push button switch versus a standard light toggle switch. Any help on this would be very much appreciated again. Thanks everyone!

[brtech]

There are several schools of thought about this, and it's very dependent on how many inputs your controller/bob has. I think the most common wiring has one input per axis, two switches per axis, combined home/limit. The most extreme is separate home switch and separate limit switches for each end of travel on each axis, but no one does that.

If you go with the combined home/limit, one input per axis, and you use mechanical switches (microswitches), you normally wire the two switches per axis in series. You tie one end of the switches in series to the power supply ground, and the other wire goes to the input on the controller/bob.

Many of us like the "electronic home switches made easy" hall-effect switches. Wiring for that is somewhat different because you have 3 wires per sensor and they can't be wired in series or parallel.

One easy way to use them is to put the sensor on the moving axis and have two magnets - one at each end of travel. Then you have one 3 conductor cable per axis, all the red (power) wires get connected to a suitable power supply +, all the black wires get connected to power ground (which is tied to your motor power ground also) and then each of the green (or whatever your 3rd conductor color is) are the inputs to the bob. I'd use a terminal block for that.

Some use the magnetic switches only for the home, and then use mechanical switches for limits. You can, if you want to, tie ALL of the limit switches in series and have one input that carries them all. That would have one input per axis for home, and one other input for all limits.

If you do that, you can use a single conductor shielded cable running around your gantry, running through each switch, using the "Normally Closed" or NC connection. You go "in" (from the prior switch) through the common connection and "out" (to the next switch) through the NC connection. The first and last switch would have wires that go to your controller. Tie one of them to power supply ground and the other to the BOB input.

Another way would be to run a two conductor cable from one end of an axis, where you connect the two wires to the common and NC connections, up to the other end, where you basically break into the cable, pull out one conductor, cut it, attach the ends to the common and NC connections of the switch, leave the other conductor alone, and continue the wire to your BOB. You do that for each axis, so you would have 3 (or 4) such cables.

If you are using combined home/limit, wire all of, say the black wires to power supply ground, and the remaining red wires are the inputs to the bob, one for each axis.

If you are using separate limits, connect each of the cables to a terminal block. Then connect, say, the red wire of one axis to the black of the next, the black of that to the red of the last axis, which leaves you with black of the first and red of the last. You connect the black to power supply ground, and the red is the limits input to the bob.

[ger21]

Many of us like the "electronic home switches made easy" hall-effect switches. Wiring for that is somewhat different because you have 3 wires per sensor and they can't be wired in series or parallel.

Yes they can. I have my Y and Z home switches paralleled together.
http://www.cnczone.com/forums/850924-post164.html

[brtech]

Huh. Didn't realize they were open drain. I read the data sheet multiple times looking for it and didn't see any spec either way.

Okay, I take it back; you can wire multiple sensors in parallel.

Gerry, why did you parallel Y and Z? Why not X and Y or X and Z? Mach seems to run its home routine for each axis separately, so in theory, you could have all three on one input. Is there a reason you didn't do that? Certainly, one input for all limits is okay.

[Al_The_Man]

Originally Posted by brtech Many of us like the "electronic home switches made easy" hall-effect switches. Wiring for that is somewhat different because you have 3 wires per sensor and they can't be wired in series or parallel.

Most, if not all hall effect sensors have open collector output, open collectors can be wired in parallel if used in a N.O. condition.
There are also 2 wire hall effect sensors with LED indication that can be used.
Al.

[ger21]

Gerry, why did you parallel Y and Z? Why not X and Y or X and Z? Mach seems to run its home routine for each axis separately, so in theory, you could have all three on one input. Is there a reason you didn't do that? Certainly, one input for all limits is okay.

I had 3 inputs available, and needed two for my slaved axis. Mach3 can be configured to home in any order, or combination of axis that you want. So right now, I can home Z first, then X and Y simultaneously.

After I had it working, I realized I could have done it with two inputs, by wiring X, Y, and Z to one pin and the slave axis (A) to the other, and homed each axis separately. That would have given me one more input, but I don't need it on this machine.

[brtech]

Got it.

Can you actually home X and A simultaneously? By default, it does it separately, which is pretty weird, since it actually bends the gantry a little doing it. Needs separate inputs for that to work of course, which as you observe would be only 2.

This helps me a bunch because I need at least one more input from my G540 to do autozero Z, and I'm using currently using all 4 inputs for X/Y/Z/A. I could get down to 2, even with separate sensors for the limits.

[ger21]

Can you actually home X and A simultaneously? By default, it does it separately, which is pretty weird, since it actually bends the gantry a little doing it. Needs separate inputs for that to work of course, which as you observe would be only 2.

Sorry for the delay, had to run and get some wrapping paper.

Yes, if the X and A are slaved, they should home together. You may need to change the homing script. If the default is this:
DoButton( 24 )
DoButton( 23 )
DoButton( 22 )
DoButton( 25 )

You'll want to remove the DoButton(25), which is the A home command. If they are slaved, the X Home command (DoButton(22))will home them both.

Some people say they need to use RefCombination(9) instead of DoButton(22).

RefCombination(9) specifically tells Mach3 to home both together.

I've tried it both ways and both work fine.

One issue I ran across, is in the Homing/Limits screen, make sure both the X and A are set to the same homing speed. You'll have serious issues if they are not the same.

[DonFrambach]

I am a newbie but I like the idea of normally closed (NC) switches because if something goes wrong with the wiring you know about it before you need to use the switch (that would not be the case with a normally open switch). Normally closed switches can't be wired in parallel but they can be wired in series (which is what I have done).