limit switches

[spaltiel]

Hi everyone,

I am trying to connect the limit switches but I am short with pins.

I am using keiling kit KL4030 + C10.

In order to wire X+ and X- and home switch i need 9 pins.

Can I connect the limit switches into the same pins and also to know which one triggered the system? because I don't think that I have so many pins available.

maybe, someone can guide me how to connect them?

thanks,
Amir

[Bubba]

Anir,
You have not stated what controller your using (Mach, Turbocnc, etc) so I can only guess. But in my controller, there is the option to use "Home as limit" and I use only one switch per axis or you could use two switches per axis and series them (NC operation only). Therefore, I need only three pins for input. Been working that way for several years now and no problems.

[metalworkz]

Hello,
You can connect the switches in series so that you use only 2 pins for all 3 switches for homing each axis. Use the automatic setup in Mach3 to get each one set up correctly and just follow the steps to trip each switch as Mach prompts you for input. That is for homing switches only. I am using soft limits in Mach3 and have not added limit switches to each axis, but I think I read that you might need another break out board to obtain enough pins in that case. I would suggest to just use soft limits in Mach and the additional limits can be added later if really needed.
Regards,

[spaltiel]

Originally Posted by Bubba Anir, You have not stated what controller your using (Mach, Turbocnc, etc) so I can only guess. But in my controller, there is the option to use "Home as limit" and I use only one switch per axis or you could use two switches per axis and series them (NC operation only). Therefore, I need only three pins for input. Been working that way for several years now and no problems.

I'm using Mach.

How do you know which switch triggered your system if the connection is series.

Amir

[spaltiel]

Originally Posted by metalworkz Hello, You can connect the switches in series so that you use only 2 pins for all 3 switches for homing each axis. Use the automatic setup in Mach3 to get each one set up correctly and just follow the steps to trip each switch as Mach prompts you for input. That is for homing switches only. I am using soft limits in Mach3 and have not added limit switches to each axis, but I think I read that you might need another break out board to obtain enough pins in that case. I would suggest to just use soft limits in Mach and the additional limits can be added later if really needed. Regards,

thanks

[Bubba]

A quick look at the switches and seeing which stop has hit the switch will tell quite quickly.

[johnmac]

With a simple series wiring setup as mentioned, Mach will not know, as more than one axis may be moving when the trip occurred. You would need to manually jog the axis away from the switch. In Mach you can also setup soft limits. Correctly setup, the machine will stop before it hits the switches.

John

[Zac.Hester]

I don't know how adventurous you want to be with the controls, but a multiplexer would allow you to wire more switches per input pins. Of course, there has to be support in your controller application (Mach?) to look at multiple input pins at once, and "decode" the bit sequence. Since you're using an off-the-shelf controller, I can't say if it will work at all, but might be worth looking into if you're really concerned about knowing which switch is tripped.

Otherwise, it is a more common solution to use normally-closed switches in series, and just live with the signal knowing only that a limit has been reached--not *which* limit has been reached.

And, like others have said, using soft limits is a completely valid option.

[I'm planning on using two 16:1 multiplexers allowing me to wire 32 digital inputs onto an 8-bit bus. My chip has a bunch of unused analog inputs, so I'm also going another step beyond and building two DACs to drop those 8-bits onto two physical pins.]

[spaltiel]

Thank you all. After reading all your comments I decided to wire all the microswitches in series.

Now I am facing wierd problem with mach 3. I can't turn ON the "override limits". after triggering the limit switch I can't jog off.

Does anyone know how to solve this problem?

thanks,
Amir

BTW i have attached few pictures of my machine (not finished yet).

[metalworkz]

Do you have the switches set up as a Home switch on each axis? How are you trying to jog when the switch is tripped? Have you tried the MPG that pops up when you hit the 'tab' key? If you have the switches set up as Home for each axis then you can check the box in 'Homing and Limits' to auto-zero the axis and then move off the switch.
Regards,

[spaltiel]

Originally Posted by metalworkz Do you have the switches set up as a Home switch on each axis? How are you trying to jog when the switch is tripped? Have you tried the MPG that pops up when you hit the 'tab' key? If you have the switches set up as Home for each axis then you can check the box in 'Homing and Limits' to auto-zero the axis and then move off the switch. Regards,

"Do you have the switches set up as a Home switch on each axis?"
I don't have Home switches only limit switches wired in series.

"How are you trying to jog when the switch is tripped?"
I'm trying to jog off using my keyboard (arrows keys) but in order to do it I understand that at first I need to press 'override limits' however it is not responding.

"Have you tried the MPG that pops up when you hit the 'tab' key"
I tried but nothing happened BTW I think it is the same as using the keyboard.

I have problem with the 'OverRide limits' which is not responding and I can't jog off the limit switches.

thanks in advance,
Amir

[metalworkz]

Hello Amir,
I don't see how the machine will be able to know where it is on any of the axis if you don't have a Home switch on them. I am using only 3 switches(1 on each axis) and each of them is set up as the Home for it's axis. When you start your machine you reference each axis to it's Home switch and then Mach3 knows what location each axis is at and keeps track of them from there. I don't know a lot about the limits set up, but I do think you need to have a Home switch for each axis. Maybe someone that knows more will reply.
Regards,