Proximity limit switch problems

[davrich]

I'll start by saying that I'm very new to all this. Chances are there is a simple solution to my problem, but as yet I haven't been able to find it.

I've built the majority of my CNC (CNC router parts Pro 4896) and I'm now looking to hook up the electronics and start the motors.

I bought the S Box control box from Marchantdice on ebay (Produced by Tonman CNC) CNC Controller 3 axis Desk top Router Mill Plasma | eBay

The one I bought was 4 axis and included pre wired E stop cables. The limit switches were the gate type switches as shown below (I'm sure that isnt the right description) and I have two wires per switch.

I'd already bought a set of proximity limit switches. New Inductive Proximity Sensor Detection Switch NPN DC 6-36V LJ12A3-4-Z/BX | eBay. As my machine has threaded limit switch holders I wanted to use that type specifically. My proximity switches have three wires, black, brown and blue. I asked Marchantdice what I needed to do to get things working. At first they suggested that I run an additional wire per switch back to the control box.

I wanted to avoid more wiring if I could, so I bought these 2 wire proximity switches, thinking that they would connect directly to my machine. LJ12A3-4-J/DZ 2-wire 4mm Tubular Inductive Proximity Sensor Switch | eBay

When I connected these to my control box the light on the box for that axis' sensor did not light up. In Mach 3 diagnostics the switch was not working when I placed metal in front of it. When I reattached the gate switch the light came on and mach 3 worked.

I then tried the 3 wire proximity switches. I connected the black and blue wires to the two leads from my control box and the light on the control box lit up, but in Mach 3 diagnostics the switch was permanently on and would not trip when metal was placed in front of it. I tried switching "active low", but that made no difference.

It seems that the gate and 3 wire switches create a circuit, whereas my 2 wire ones didnt.

I asked Marchantdice again and they suggested that I buy another set of cabling from them, with proximity limit switches already attached. Having already spent approx £40 on two sets of limit switches and already having cabling obviously I'm not willing to pay out even more before I explore other possibilities.

I don't have much information re the S Box. It came with no instructions, Marchantdice web pages offer limited info and the manufacturer's website is in Chinese.

Ideally I want to use a 2 wire proximity switch to make use of the cabling I have. I really hope that someone has a quick and easy answer to this because my build has hit a brick wall.

I see that there are different types of proximity switches - NPN, NC etc. Do I just need two wire NPN limit switches by any chance?

Thanks in advance for any help.

David