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In Mach 3 I have pin 1 set fir XYZ limits and pin 4 set for XYZ home. To wire limit switches as normally closed, can I wire the two limit switches on each axis seperately and connect them by way of a splitter to my two lead wires coming from my controller? Please se attached diagram .

When wiring the limit/home switches on the NC terminals, the output of one switch (NC terminal) needs to connect to the input (Common terminal) of the next switch (wired in series). The three home switches are one set that get connected together, and the three limit switches are a separate set which get connected together. The input pin would be configured as Active Low. The downside to this arrangement is that current is flowing through the home switches when the machine is not homed, and always flowing through the limit switches when the machine is not at a limit. That is, current is flowing most of the time that the machine is working.

The alternative is to use the NO terminal. Each switch is independent, and the outputs are wired in parallel. The input pin would be configured as Active High, and current would only flow through a switch when that axis is homed or has reached its limit.

The other difference with your drawing is that you are sending +24v out to the machine environment, where a chafed wire could cause a short. The safer method is to use ground-based logic, where +24v stays within the control box, and the switches in the machine environment connect to ground.

Two drawings attached.

fsli wrote:When wiring the limit/home switches on the NC terminals, the output of one switch (NC terminal) needs to connect to the input (Common terminal) of the next switch (wired in series). The three home switches are one set that get connected together, and the three limit switches are a separate set which get connected together. The input pin would be configured as Active Low. The downside to this arrangement is that current is flowing through the home switches when the machine is not homed, and always flowing through the limit switches when the machine is not at a limit. That is, current is flowing most of the time that the machine is working.

The alternative is to use the NO terminal. Each switch is independent, and the outputs are wired in parallel. The input pin would be configured as Active High, and current would only flow through a switch when that axis is homed or has reached its limit.

The other difference with your drawing is that you are sending +24v out to the machine environment, where a chafed wire could cause a short. The safer method is to use ground-based logic, where +24v stays within the control box, and the switches in the machine environment connect to ground.

Two drawings attached.

So the limit swithes must be linked together in one continuous loop. I can't wire each axis seperately and wire them into a splitter that connects to the two connection wires coming from the controller correct?

Depends how you want to do it.
If they're NC switches and you're using 6 you can link all in series to 1 input. But then need another 3 for home.
You can wire 3 sets of 2 switches in series to each axis and use 3 inputs for xyz. Again need 3 more for home.

You could wire 3 switches in series to the - end of the 3 axis to 1 input (limit). Then wire 3 switches in series to the + end of the 3 axis to 1 input (home/limit). Then set the + ones as home switches.

If you have 6 inputs available you can wire them individually for xyz +/-, you can add a basic bob to port 3 to create some more inputs if needed. Then you can assign any 3 as home switches. Best option.

You can also do it using only 3 switches on 1 end of each axis wiring individually direct to 3 inputs for xyz. I believe you can use them as home as well. This is prob the easier option.

There's a few options.

Dazp1976 wrote:Depends how you want to do it.
If they're NC switches and you're using 6 you can link all in series to 1 input. But then need another 3 for home.
You can wire 3 sets of 2 switches in series to each axis and use 3 inputs for xyz. Again need 3 more for home.

You could wire 3 switches in series to the - end of the 3 axis to 1 input (limit). Then wire 3 switches in series to the + end of the 3 axis to 1 input (home/limit). Then set the + ones as home switches.

If you have 6 inputs available you can wire them individually for xyz +/-, you can add a basic bob to port 3 to create some more inputs if needed. Then you can assign any 3 as home switches. Best option.

You can also do it using only 3 switches on 1 end of each axis wiring individually direct to 3 inputs for xyz. I believe you can use them as home as well. This is prob the easier option.

There's a few options.

Look at my wiring scheme, this is how UCCNC told me to wire the inputs, see if that looks correct to you. I can't get the limit switches to work. The 24V+ wire and the black input + wire are the two wires that make up my 2 pin connector at the box.

gills wrote:So the limit swithes must be linked together in one continuous loop. I can't wire each axis seperately and wire them into a splitter that connects to the two connection wires coming from the controller correct?

Correct (you can't do it that way). If you want to connect the X home in series with the X limit switch, as you showed in your original drawing, then you'll need three different input pins: one each for X, Y, and Z.

My second drawing, which uses the normally-open contacts on the switches, is the closest thing to using a "splitter" (distribution block), but you'll need two splitters: one for the home switches and another for the limit switches. If you look at that drawing, consider that all the ground connections on the six common terminals could come from one splitter. The three NO outputs from the home switches are connected together in what could be seen as another splitter running to your first input pin. The three NO outputs from the limit switches are connected together in what would be another splitter that runs to your second input pin.

gills wrote:Look at my wiring scheme, this is how UCCNC told me to wire the inputs, see if that looks correct to you. I can't get the limit switches to work. The 24V+ wire and the black input + wire are the two wires that make up my 2 pin connector at the box.

This second drawing that you provided is correct if you're using the arrangement I showed in my first drawing (X, Y, and Z home switches in series, and separately the X, Y, and Z limit switches in series). The only difference, as I mentioned earlier, is that the arrangement in both your drawings requires that +V be sent to the switches. It's just a reverse of how I'd prefer to do it (ground at the switches, power inside the control box).

Of the 6 inputs, currently I1 is home, I2 is Touch probe, I3 is E-stop, I4 is limit. I5, I6 are open. If home requires a separate input for each axis, I can tag I5,I6 for the other 2 axis and leave the limit switches on one correct?

Ok so what do I have wrong in my wiring? I have tried wiring 3 NC switches together in series, and 3 NO switches together in parallel and neither is triggering in mach 3 when I engage them. My estop works, my VFD spindle is working fine, but these limit switches are stumping me.

gills wrote:Ok so what do I have wrong in my wiring?

I'm not in your workshop to see what you did wrong. Got a picture of the AXBB-E, as-wired?

Question: Does the LED on the input port(s) light up at all? Either when the home/limit is triggered, or when the machine is not homed/limited?