Wiring Limits

[freecr]

Can someone please clear up a few questions I have dealing with wiring and configuring the Limit switches?  Hi, I'm new to this stuff in all ways possible.  I'm usually pretty good on this sort of thing but find myself confused right at the beginning.  I'm converting a Fryer bed mill from an Anilam control to Mach 3.  I have a Galil DMC-4040 Accelera controller.  I'm currently trying to hook everything up.  I am trying to reuse as much as possible and while more bells and whistles are nice and some are very possibly future additions, I only right now need a pretty basic setup.  It’s a three axis bed mill with all three axis's having identical servos, amps, encoders, and limit switches.  I have everything mounted and now have to wire the limits.  Galil allows the power for the switches to come from either the controller itself or from an external source.  The question is why is it suggested to use an external source?  It seems to be just another thing that can go bad.  I have a power supply handy and can mount and wire it but why should I?  It seems greatly simplified just to use the onboard Galil +5v.  Currently I have only one limit switch per axis, the forward (+) limit.  There is a box to check for configuring of the Galil Plugin for Mach 3 that allows using the Limits for Homes.  So the second dumb question is which Limit switch does it choose for the home?  I think I can assume it’ll choose the forward (+) switch as that is probably convention but I would like to confirm that as I don’t have reverse (-) Limit switches.  This leads me to another question…if I don’t have a reverse (-) Limit switch what do I do?  The switches are normally closed so if it thinks I have a reverse Limit switch it would think it’s tripped and fault, right?  Do I just jump the RLSx to the ground or is there a way to tell Galil and Mach 3 there isn’t a switch in the first place?  My final question of the day involves what might be just wiring vs. configuring.  For wiring I was going to wire the pos (+) wire from whichever source to the LSCOM (#6), the ground likewise from whatever source to one end of the switch, and finally the other end of the switch to FLSx(#36,37,38,39).  But in the manual All use port #1:  X +limit = pin #1, Y +limit = pin #2, and Z +limit = pin #3.  What is this about?  I’m still in the wiring stage and it may just be a configuring (ie later) step.

Thanks to anyone that can shed some light on any or some or all of these questions.

[Fastest1]

Ok, there are a few things here. I am on my phone so I will summarize. First a single limit switch can be used on each axis just fine. You may use 1 or 3 pins. During your set up of home and limits in Mach you will tell the machine. In which direction the switch will be. During homing it will go that direction and upon the switch closing it will back of til the switch opens. If you have the limit set as a home switch also it will go to a home position (a coordinate you determined ahead of time, a good place to change your stock or tool). Since you only have 1 limit per axis you will set up soft limits. These are a physical distance from the switch to the end of travel the opposite direction (not quite the full travel but close). The machine will not pass the soft limit. It will also prevent you from starting a file if it sees it will cross the boundary. There is more to it than just this simple answer but this is the idea.

[Fastest1]

Btw, using only 1 pin for all of the switches will only allow for axis to be homed one at a time. Not really a problem for the hobbyist as it only takes a few more seconds but if production was your intent, seconds count.

[freecr]

Thanks Fastest1,

I was hoping that was going to be the answer.  I went ahead and wired the switches last night using an external power supply instead of from the Galil board.  One pin is shared by all three switches the ground from external power supply, the +5VDC going to the LSCOM.  The other end of the switch I have connected to FLSA, FLSB, and FLSC inputs.  I am just a hobbyist and all I have is time.  The Anilam system that died which I'm replacing homed one axis at a time and I guess that is what I'm used to anyway.  I have questions galore with the wiring (the easy part), I cant wait how many questions I have once I start configuring it software wise.  Now that the limits are wired, I think; I get to move onto wiring the encoder.   Eight wires coming out of it!  So I'll read the manuals and search the threads and see how many answers I can find.

Thanks so much for the help!

[Fastest1]

Sure, don't forget there is an electronics section here. There are some great guys there that will help with the encoder or any other electrical/electronics issues. Sometimes you get better help in a specific forum, I just try them all til I get an answer. If I can help I will. That isn't saying much! LOL

[Fastest1]

Sorry, I forgot which forum I was on. Though there are many here just as helpful, I also use "CncZone" which has the electronic section I was mentioning. If you aren't a member there yet, join up, it is free like here and very helpful in so many ways to a person starting out or very experienced for that matter.