Endstop Wiring

  • So, have the old mechanical 3-wire endstops on my P3 Steel and have been tryingt to get these to work with the Duet WiFi. The wires are labeled


    and I have connected the Com (SIG?) and NO (GND) to pins 1 and 3 on the Molex, leaving the NC (3.3V) unattached..

    Using M119 I see the states of the Endstops and then hold the endstop switch closed and try M119 again and nothing, no change .. so based on previous experience, I am doing something wrong ..

    Any thoughts?

    config - M574 X1 Y1 Z0 S1 ; set endstop configuration (X and Y endstops only, at low end, active high)

    M119 returns:

    5:16:40 PM M119
    Endstops - X: at min stop, Y: at min stop, Z: not stopped, Z probe: not stopped

  • administrators

    If it's a bare switch, it's better to connect COM and NC to the outer 2 pins of the endstop connector (it doesn't matter which way round). If it's a small PCB with the switch mounted on it and 3 or 4 connections to it, then there is also an LED on the small PCB which complicates matters, so see https://duet3d.com/wiki/Connecting_endstop_switches#Makerbot_Mechanical_Endstop_v1.2.

  • Hi,
    tried it and it made no difference.. Also tried on Y, X and Z stop connectors and no difference ..
    It is a bare switch ..

  • administrators

    Watch the endstop LEDs on the Duet. They should be lit up when the corresponding endstop is connected but not triggered, and unlit when the endstop is triggered or no switch connected.

  • More news .. I used the old style dupont connector and cut the NO wire and it works.. A red light is lite when I start up on the X and then the light goes out when I close the switch .. M199 returns proper values as well ..Maybe I am doing something wrong with the molex connector.. hope not, I converted all steppers over to them ..

  • X and Y are working this way now .. have to figure out what I am doing wrong with the molex connector fasteners ?..

  • administrators

    As long as you don't have the centre pin (+3.3V) of the endstop switch connector connected to your switch, you should be OK. If you did have it connected to the switch, you were quite probably shorting the 3.3V supply of the Duet to ground. But unlike Arduino/RAMPS, the Duets are designed to tolerate this without damage in most cases. We really don't like our customers spending a lot of money on a premium product and then damaging them because of mis-wiring! And as a safety engineer, it's natural for me to be thinking "what if?" when I design things.

  • The center wire is cut and taped, so should not be a problem .. I watched some videos on the Proper way to crimp a molex connector, not all that different from a Dupont .. is it common to have problems with these or should I be looking elsewhere for instructions on inserting these?
    Thanks again..

  • administrators

    Crimping Molex and Dupont connectors is very similar, however their dimensions are different in subtle ways. The crimp tool I have will crimp Molex connectors reliably. But when I use it to crimp Dupont connectors, about one time in ten I end up with a bad connection. So I always test the cable with a multimeter after crimping the ends.

  • It looks like that was it.. I pulled the molex and replaced with a dupont and all three end stops are working now .. thanks again .. I am using a PA-09 for my duponts and tried it with the molex but obviously it didn't work as well for me .. will look into it .. I have four steppers that have already been converted .. will need to test them all .. What crimp tool do you use with the molex?

  • administrators

    The crimp tool I use for Molex connectors is a very old one that is no longer made. I have heard that HT-225D (widely available on eBay) is suitable.

  • @dc42 said in Endstop Wiring:


    I have something very similar from eBay, but when I crimp it smashes the connector until it breaks

Log in to reply