Limit switch to Diagram Print Question. .

[countryguy]

Getting closer gang! I did search thru the Limit Switch posts. 131... I'm going to just ask as I'm so short of time anymore.

1 Limit switch per Axis.
1 cable from switch.
Three wires per cable on a wire block.
Common and a wire for each end of the max range. Tripped by an adj. stop on the mill.
Normally closed. Upon hitting stop, Switch goes open.

For the wiring diagram- I believe I use 1 cable per axis.

Wire all the commons to TB1 13,14,15.

Wire the appropriate + or - *limit wire to the H11 1-4 and 5 & 6.

*Note- for proper movement of + or - wire, Use the pic on the Operators manual, Page 11 of PDF. Not sheet.

[countryguy]

Hi all - Sorry if that Q above did not make any sense? So on the limits. If you have a single switch for the X axis with a common and two poles. (3 wires) do you simply wire the common to the PS1 TB1 ground (as noted on print) and then run the switches other two wires to the X+ and X- hookups?

Also on mine, the switches are NC (shorted) and go Open upon breaking the limit.

I'm pretty sure I wire it up as noted above so I'll proceed for now. Best ,
Cg /

[cncsnw]

In your first post, you seem to be saying that you plan to hook up three wires to one switch, and somehow use that one switch as both a plus limit and a minus limit for the axis.

If that is what you meant, then the answer is no: it does not work that way.

For each limit switch you are going to install (and ideally you want six limit switches: X-, X+, Y-, Y+, Z- and Z+), you need one normally-closed switch. To wire one normally-closed switch, you need two wires. One wire goes to the DC common on TB1. The other wire goes to the appropriate limit switch input terminal on the PLC.

If you only have one switch for each axis, and you do not plan to install additional switches, then you have to decide whether that one switch is going to be the minus limit or the plus limit, and wire it accordingly (with two wires). Then you have to trust the software limits to prevent you from running all the way to the switch or hard stop at the other end.

If your machine is set up so that the switch can trip at both ends, and you allow it to do so -- say you have the switch wired and configured as the X- limit, and you move X+ beyond normal travels and trip that same switch -- then you will be unable to jog the axis back off the switch. The only way to get off the switch will be to turn the ballscrew by hand. That is because, as the X- limit, the switch prevents the control from moving the X axis in the minus direction.

[countryguy]

I know Limits seem to blow us Newbs up... Thanks for working with me. I did post a pic of what I have here:
http://www.cnczone.com/forums/ajaxcnc-c ... ost1655046

I think it is as you described. Soft limits and pick 1?