Wire Limit Switches at Axis end

Wiring the Limit Switches at the Axis’s.

Limit Switches are used to let you software know when an axis has come close to or is at the limit of it’s physical movement. They work by being put in such a position that when an axis is near the end of it’s travel it will come in contact with it. This will complete a circuit that is wired back to the a Breakout board which in turn sends a signal to you controller software (Mach3 etc). Once tripped a limit event is registered in Mach3 (or your other software) and all machining will stop, the machine will be in same condition as if the E-Stop button has been triggered.

There are several different ways to wire these up, with the 2 more common methods being Serial and Parallel.

Serial: The easiest way to explain Serial, is that the signal travels through a circuit in a continuous loop. All the switches in the circuit are wired as NC (Normally Closed). The signal will travel along a wire, in to a switch, out the other side and on to the next switch in the circuit. This type of circuit would always be active (on), so any break in the signal (contact at any switch) will initiate a limit event.

Parallel: This method divides the circuit in to halves with the active signal being on one side and the common on the other. The switches act as bridges between the two halves and are wired as NO (Normally Open). Contacting a switch will close a bridge (complete the circuit) and a limit event will be triggered.

The Primarily function of all this is to stop your axis’s from crashing into their mounts and causing damage to your components.

These instructions will cover how to wire your Limit Switches using the Serial method.

Why Serial? The Serial method offers an addition layer of protection some of the other methods don’t. As Serial is always on any break in the current will signal a limit event. This is handy as you have wires that physically move as your machine does. These wires can break (internally or externally), dislodge or become disconnected in someway. As soon as this happens a limit event will register, you may not know where the issue is immediately but at least you will know there is one. With “Parallel” the current is only present when a switch is contacted, however if the current has been cut by a broken wire and a switch is contacted, no signal will be sent. Your only indication something is wrong is when your axis reaches the end of it’s travel an tries to keep going.


AC Mains Power can kill or seriously injure

DO NOT plug in your equipment while you are working on it

Never add or remove wires from/to your Breakout Board while it is powered up as it may permanently damage it

  Parts Required

Supplied Parts

6 x Mounted Limit Switches

12 x 4.8mm Spade terminals and covers

3 x Twisted Pair Wiring set (or Additional Wire Set) (optional)

1 x Rail Connector (optional)


Parts to be sourced

Qty? x Meter 2 pair (2 wires run together) wire sufficient to run from the JK02-M Breakout board to the Limit Switches. During the “Wiring Steppes” instructions it was suggested you could run 6 core cable, the remaining 2 cores will now be used. If you did not run 6 core cable you will need to source some 2 core cable. Ethernet/Network cable is ideal and cost effective.

4 x Wire hold downs or clips to hold the wire in place at the enclosure end of the cable.


Recommended tools

Wire stripper

Wire cutter

Crimping tool

Flat head screwdriver (small)

Philips head screwdriver (small)

Soldering iron and solder (optional)

Parts Overview

Limit Switch

  1. Terminal 1 (Signal in)
  2. Terminal 2 (Normally Closed circuit out)
  3. Terminal 3 (Normally Open circuit out)
  4. Roller and Switch lever
  5. Switch actuator
  6. Switch housing
  7. M3 Mounting points

Required/Recommend Steps Before these instructions

Mounting limit switches

Connecting Stepper motors to DIV268N Stepper Driver

Assembly/Installation process

These instructions will cover wiring the Limit Switches at the Axis. Positions of parts and lengths of wires  used are for instruction only and may vary from your actual setup and you will have to interpret/vary these instructions to meet your own needs. All parts and wiring from previous instructions have been omitted in an effort not to over complicate the images.

Wiring at the Limit Switches

The best wire for this task is the twisted pair in your kit, however you can use the additional wire kit if you find these instructions difficult to follow with twisted pair. I was not able to draw the twisted pair correctly so I have ended up just drawing the wires from point to point, you will have to use your imagination, I was also not able to show the different stripes on wires either.

Why use twisted pair? Well it’s designed to carry a signal better and the actual twisting of one wire around another aids in maintaining signal integrity.

Running and terminating wire for the Limit Switches

Taking into account your wiring choice you’ll need to run your limit switch cable through your machine and to your limit switches. You will also need to terminate or anchor your wiring in some manner.

If you chose to run 6 core wire to the stepper motor with  intention of using the additional two wires for the limit switches then this step is almost complete. You will simply need to terminate the two remaining wires into the terminal block.

If you have run a specific cable to the limit switches you can either terminate it with some Rail Terminals or wire the cable directly to the switches.


To terminate with some Rail Terminal, cut off 2 terminals with a craft knife and affix them to the surface of your router somewhere between the switches with an appropriate screw.

Run your wire pair up to the Rail Terminals, allow an extra 10mm and cut. Strip each wire back approx 6mm and give a twist to bind any loose fibers.  

Loosen of the lower terminals with a small Philip’s head screwdriver and insert the wires. Re-tighten both terminals.

If you have limited wire colours at your disposal and are going to have to use them again it is advisable that if possible use the same wire colour for negative each time, in the example above “white” has been used for negative and “brown” for positive. Negative and positive are only “Notional”

Wiring Positive and Negative to the Switches from a Terminal block

Select either a set of twisted pair or two wires from your Auxiliary wire kit and strip each wire back approx 5-6mm and give a twist to bind any loose fibers. If possible use the same colour wires as already run. For this example the “brown” is the positive and white is negative.

Loosen off the upper terminals on your Terminal block with a small Philip’s head screwdriver and insert the wires. Re-tighten both terminals



Run the Positive (Brown) wire to terminal 2 (NC) on your left limit switch and the Negative (White) wire to terminal 2 (NC) on the right limit switch. Leave about 6mm of additional wire and cut.

Strip each end of the wire back approx 5-6mm and attach a 4.8mm spade connector to each end by crimping or soldering (soldering preferred). Remember to slip the clear spade terminal covers (not pictured) on to the wires before attaching terminals.

Connect the Positive wire to terminal 2 (NC) on your left limit switch and the Negative wire to terminal 2 (NC) on the right limit switch.

Wire the cable directly to the switches

The process is almost exactly the same as above just without the terminal blocks in-between. The only difference is that you will need a hold down clip of some sort to anchor your wiring to your machine. It could be skipped but I recommend it as your wiring will be loose and may snag and disconnect/break loose during machine movement.

Connecting the limit switches’ common terminals together

Locate the “Common” terminals on the limit switches (labelled as Terminal 1 in the parts overview).

Run a length of wire between the Common terminals and adding an additional 10mm to each end.

Strip each end of the wire back approx 5-6mm and attach a 4.8mm spade connector to each end by crimping or soldering (soldering preferred). Remember to slip the clear spade terminal covers (not pictured) on to the wires before attaching terminals.

Attach the wire to both of the Common terminals on the limit switches.

Your axis is now wired and should resemble one of the images below:

Straight Through

Via a Terminal Block

Using the same terminal block as the stepper motor

Wiring Multiple Axis’s

Repeat the above steps to wire your other two axis’s. Remember to note which wire set goes to which axis as you’ll need to know this information when wiring the limit switches to the breakout board.

Wiring back to your enclosure


Prior to testing the instructions for wiring limit switches to your breakout board and configuring ports and pins for your breakout will need to be completed.

Supplementary Images


Next Step

Wiring Limit Switches to the JK02-M Breakout Board

Wiring Limit Switches to the TB6560 Driver Board