limit switches

[superpot]

Hi everyone a quick question if I may as electrics \ electronics is not my forte.
I am ready to wire in my limit switches for X,Y & Z axis. They are wired to the NC position and I get the commons can all be joined together and connected to a common terminal but am I correct in thinking that the "lives" are all connected and one wire then goes into input 2 on acorn board? Also is it correct for me to also pass a link \ bridge wire from the collective "lives" to the input 1 to allow me to home all using the same switches?

If the "lives" are all connected in series \ daisy chained into input 2 and one trips how does acorn know which one has tripped?

forgive my ignorance,

[Chaz]

Hi,

Have you taken a look at the various schematics from the website? They show a lot of examples on how to wire limits.

[superpot]

yes I have but as I am not confident I prefer to ask the experts Chaz

[ShawnM]

Superpot,

Umm, the experts are the ones who created the wiring diagrams. Have a look at diagram S14954 and it clearly explains how to wire N/C and N/O switches. They actually show a diagram for N/C switches and how they are wired in series. Your thinking is not correct so please have a look at the diagram and get familiar with how these switches work.

What type of machine you are wiring these to would be helpful for us to know and where "physically" are you putting these switches?

You say you are installing 3 "limit" switches, do you mean 3 "home" switches? Are you just installing 3 switches at one end of travel and will use the software limits on the opposite end of travel? This is fairly common and works very well. Can we assume these are mechanical switches and not proximity switches? Be a bit more specific if you can. You need "home" switches for the auto home sequence to work, limit switches are optional.

I'm by no stretch of the word an expert but you want to wire your N/C switches in series to one input to save inputs. If these are actually "home" switches, when the machine is running the auto homing sequence it only moves one axis at a time to the home switches. It doesn't really need to know which switch in the series tripped only that one did, then it moves on to the next axis in the homing sequence. Once it homes your x,y and z it sets that as machine coordinate zero and you can't travel past that position in. Then you can set the software limits in the wizard for max travel and the machine, once homed at startup, will not travel past those limits. It's just smart like that.

[superpot]

Thank you Shawn. The machine is a knee mill and I have placed physical mechanical limit switches at each end of each axis. I think after seeing the diagrams I understand how they need to be wired in series. I can set the software limits up afterwards and set them say 5mm before the mechanical switches as per Marty's videos. I am thinking of using the same switches for the home switches but may not bother as I can do a simple home on each start up as it suits me better as I like to leave the bed in the central position because of strain if parked fully over to one side if that makes any sense?

[martyscncgarage]

Hi everyone a quick question if I may as electrics \ electronics is not my forte.
I am ready to wire in my limit switches for X,Y & Z axis. They are wired to the NC position and I get the commons can all be joined together and connected to a common terminal but am I correct in thinking that the "lives" are all connected and one wire then goes into input 2 on acorn board? Also is it correct for me to also pass a link \ bridge wire from the collective "lives" to the input 1 to allow me to home all using the same switches?

If the "lives" are all connected in series \ daisy chained into input 2 and one trips how does acorn know which one has tripped?

forgive my ignorance,

The schematics are your friend. Tell us WHICH one you are using?
It sounds to me like you want to use ONE input and use home all. If so, then no, your thought above is not correct.
Start with X.
LS wire goes to COM, the other goes to a Y limit switch wire, the other Y limit switch wire goes to a Z limit switch wire. The last Z wire goes to an input . (Usually input 1)
The theory is that the 3 switches are all wired in series any one of them breaks the circuit. Does this help?
See attached HOMEALL LIMIT ALL schematic. (Limit all is the OPPOSITE end of the machine travel wired in the same manner)

If it were me, I would let the machine home itself to the switches and not rely on simple home. Why? Because your soft limits may not be accurate when using Simple home, unless you mark each axis and line up the marks and then use Simple Home.

[superpot]

Thanks Marty, I am awaiting some connectors which should arrive tomorrow and then I can test the switches which have been wired in series to that diagram but to limit switches on input 2

[martyscncgarage]

Thanks Marty, I am awaiting some connectors which should arrive tomorrow and then I can test the switches which have been wired in series to that diagram but to limit switches on input 2

Just remember HOMEALL is for homing the machine. LIMIT ALL is placing a safety at the end of the machine.

What kind of mill are you working with? Would be nice if you posted a picture of the machine.

Marty

[ShawnM]

A widely used practice would be to place home switches on one end of travel so the machine can auto home itself and set the far limits in the wizard with the software limits. This way the machine will know it's full travel limits every time.

Simple home wont work as you described with the software limits because you'll never be able to precisely simple home it in the same spot each time. I think you may be over complicating your setup but if you want all those switches you can certainly do that. It's just not needed, the auto home and software limits have not failed me in over a year on two different machines. It just works and it's simple.

You can still park the machine at the end of the day in the center so all the weight is right over the base of the machine. In fact if you use home switches and auto home at start up the machine will know it's full travel limits and you can then add a button to the VCP that says "park" and at the end of the day click that button and the machine will move to it's defined "center of table" automatically before you shut down.

[superpot]

That sounds exactly what I am hoping to achieve Shawn. I attach a few photos of my machine albeit slightly untidy.

https://drive.google.com/drive/folders/ ... sp=sharing